Will Monza expose Mercedes' vulnerability again?

Mercedes remains Formula 1's undoubted dominant force, but could its baffling performance slump in qualifying at last week's Belgian Grand Prix represent a slight chink in what otherwise seems like impenetrable armour - a small crumb of comfort on which its rivals might seize in Italy?

Mercedes brought a decent engine upgrade to Spa and Nico Rosberg trounced his F1 opposition in Q2 using the soft compound Pirelli tyre, quicker than Red Bull's Max Verstappen could go on the super-soft, which was estimated to be slightly north of a second faster than its yellow-banded cousin. Perfectly predictable on a circuit that suits Mercedes so well.

But when Rosberg bolted on the super-softs for Q3 he found less than a quarter of a second - that's at least 75% less of an improvement than expected. Verstappen ended up only 0.149s slower than F1's fastest car; Ferrari's Kimi Raikkonen felt sure he'd have snatched pole but for a mistake at the final corner.

It seemed as though there still might be an obvious explanation for this surprising underperformance - at a circuit where Mercedes has been untouchable in qualifying during the V6 era.

Mercedes had taken a severely limited number of super-soft tyres to Belgium and therefore had done little running on that tyre ahead of qualifying. Surely with more running it would have found a better set-up and then extracted a better performance from the car.

Technical chief Paddy Lowe reckoned not, saying it wouldn't have mattered how many sets of super-softs Mercedes threw at the W07, the result would have remained the same.

On the rare occasions Mercedes has looked vulnerable in recent times - beyond simple mistakes or its drivers crashing into each other - it has usually had something to do with failing to get the sensitive Pirelli tyres working properly in certain conditions at a particular circuit.

This remains an imperfect black art - affected by the complex mixture of track surface, weather conditions, car set-up and tyre pressures all interacting with one another.

It's no secret that Pirelli has imposed stricter limits on tyre pressures and camber settings in recent times, to prevent teams over-stressing the tyres and causing failures.

At Spa there were many complaints about "crazy" tyre pressure limits that were making the cars feel vague to the drivers, and causing teams headaches in terms of how to set them up to best extract performance.

These difficulties were exacerbated in searing heat, which made it extremely difficult to keep the super-soft tyres working in a sensible way over a single lap, never mind a longer run.

This brought Mercedes back towards the field at Spa, as it struggled to extract the extra performance that should have been available from a quicker compound.

The problem was that Mercedes couldn't keep the tyre from overheating, and Pirelli's high starting pressures combined with unusually high ambient and track temperatures limited Mercedes' ability to utilise any advantages it held in terms of downforce and power.

Mercedes still went on to win the race comfortably, but had to follow some unusual set-up directions to do so, and team boss Toto Wolff expressed frustration at what essentially amounts to a mandated limit on his car's performance.

"All our simulations are being hurt by a tyre that is completely different in behaviour than we were expecting," he explained. "We have been consistent in our development, and putting the car on the track in a way we felt was right, and then you're thrown off the track a little bit on a Friday or Saturday because the behaviour is completely different than expected.

"We've got a car with a lot of downforce, and that is hurting us because we aren't able to put the downforce on track."

How unusual to think of Formula 1 in this way. For so long downforce has been the unencumbered holy grail of performance - find it in the factory, bolt it onto the car, go faster. Provided your simulations are accurate of course...

But now it seems the control tyres can potentially place an artificial ceiling on how much aerodynamic performance it is possible to extract from a given car.

The old rules still apply to a large degree - Mercedes is still on top after all - but now those rules can be bent out of shape by limitations imposed by the tyres in certain conditions.

It seems Mercedes is reaching the stage where it has evolved its car past the point at which the tyre can cope with the loads it produces, while Pirelli is constantly having to raise tyre pressures as a safeguard against possible failures.

But this narrows the contact patch, which in turn limits the total amount of load it's possible to put through the tyre, which seems to limit the ability of the W07 to properly stretch its legs.

"We saw it was really close in qualifying [at Spa] so we're expecting a similar situation again," reckoned Mercedes driver Nico Rosberg ahead of practice for the Italian Grand Prix at Monza. "With the track being shorter as well here, it could be close.

"It's a bit saturated, the super-soft. With the [high] temperature it comes to a limit and all the teams close up."

That was certainly true at Spa, and here at Monza the conditions were similarly hot for Friday practice - 29C ambient and track temperatures in excess of 40 degrees - while the teams are again using the super-soft compound (which is of a low working range and this easy to overheat) at a circuit that tyre was not designed for originally.

So perhaps there is a glimmer of hope for Mercedes' rivals - to chase a target that is not static exactly, but perhaps not moving away as fast as it once did?

Rosberg struggled to progress on the super-soft at Spa, lapping impressively in 1m48.348s in the first practice session, but then slipping back to 1m48.742s on Saturday morning before finally doing just about enough to bag pole on a 1m46.744s lap with everything turned up.

By contrast Ferrari consistently progressed from Sebastian Vettel's 1m49.023s opening gambit in second practice to Raikkonen's 1m46.910s best in Q3. Similarly Verstappen topped Friday afternoon with a 1m48.085s lap on super-softs and come qualifying worked down to 1m46.893s despite missing final practice with a gearbox problem.

At Monza Mercedes has more super-soft tyres available and ran the compound in both free practice sessions here on Friday.

Rosberg topped the opening session with a 1m22.959s lap, a couple of tenths up on team-mate Lewis Hamilton and 1.088s clear of Kimi Raikkonen's Ferrari and its newly updated engine.

Hamilton turned tables in the afternoon, but only bettered Rosberg's earlier effort by 0.158s, while Vettel found over a second between sessions and got his Ferrari to within 0.453s of Hamilton's pace.

PURE PACE RANKING
1. Mercedes (Hamilton) 1m22.801s
2. Ferrari (Vettel) 1m23.254s
3. Red Bull (Verstappen) 1m23.732s
4. McLaren (Alonso) 1m24.253s
5. Williams (Bottas) 1m24.299s
6. Haas (Grosjean) 1m24.516s
7. Force India (Hulkenberg) 1m24.587s
8. Sauber (Ericsson) 1m24.981s
9. Manor (Wehrlein) 1m25.083s
10. Toro Rosso (Sainz) 1m25.240s
11. Renault (Magnussen) 1m25.555s

Mercedes obviously has an advantage here as it stands, but the question is whether it can continue to find more time on the super-soft tyre as performance ramps up in hot conditions that look set to remain similar for the rest of the weekend.

Some teams were complaining about overheating and blistering from the rear tyres - which is exactly what Mercedes struggled with at Spa - but Monza is a very different circuit layout that does not require the same compromise between downforce and drag.

There is no twisty middle sector to deal with here - just a lot of flat-out driving with a few chicanes and a couple of quick but open corners at the Lesmos and Parabolica.

This means the tyres are under less strain across a lap through the corners here than at Spa, and have better opportunity to recover their composure on the straights.

"Spa was a different story," explained Pirelli racing manager Mario Isola. "There were a lot of high-speed corners with high loads on the tyres, a long lap, and here you have long straights, less downforce, so it's a completely different situation."

Certainly Rosberg's feedback after Friday practice was that Mercedes is in much better shape here.

"The tyres seem to be working much better than expected, whereas in Spa they were overheating too much," he said. "It's different from Spa, because today I felt really good in the car straight away. We got the balance pretty much right and after that it was a good battle with Lewis.

"Ferrari seemed to have made progress with their engine, but we had our engines turned down, so we cannot compare directly.

"Let's wait for qualifying to see where we all are. I'm optimistic for qualifying - confident I'll be ahead but they're not too far off."

Whatever tyre struggles Mercedes suffered with specifically at Spa, it does not seem to have carried them across to this circuit. And the layout seems to be helping keep the super-soft under better control over longer runs, despite the cars running in a lower downforce specification and so being prone to more sliding and overheating of the tyre.

LONG RUN RANKING (super-soft)
1. Mercedes (Hamilton) 1m27.004s (12-lap average)
2. Red Bull (Verstappen) 1m27.921s (10-lap average)
3. Ferrari (Raikkonen) 1m28.030s (10-lap average)
4. Williams (Bottas) 1m28.048s (10-lap average)
5. Force India (Hulkenberg) 1m28.384s (8-lap average)
6. Renault (Palmer) 1m28.506s (12-lap average)
7. McLaren (Button) 1m28.814s (9-lap average)
8. Sauber (Ericsson) 1m29.025s (7-lap average)
9. Haas (Gutierrez) 1m29.034s (13-lap average)
10. Manor (Wehrlein) 1m29.035s (7-lap average)
11. Toro Rosso (Sainz) 1m29.127s (11-lap average)

Hamilton and Rosberg both comfortably tallied double figures for consecutive laps completed on the super-soft over longer runs, experiencing a gradual drop-off in lap time but holding on to the tyre much better than their main rivals.

Red Bull and Ferrari are well adrift at the moment, both in terms of pace and degradation, and falling back towards the clutches of Williams.

Mercedes is even further clear on the soft compound, Hamilton averaging 1.5s per lap faster over a 12-lap stint compared to Vettel's equivalent 18-lap run. Daniel Ricciardo's Red Bull lapped fairly consistently for 15 laps, but another tenth and a half per lap slower than Vettel on average.

So it seems Mercedes holds all the aces here again, despite its super-soft tyre struggles last time out, Ferrari's engine update for this race, and Red Bull's recent improving form.

That brief window of opportunity, slightly opened at Spa, seems to have been slammed firmly shut again, despite the carryover of tyre compound and prevailing conditions.

The Tifosi will have to hope Mercedes fails to find much more from the super-soft tyre on Saturday, while banking on their beloved Ferrari extracting enough extra performance from its encouraging new engine package to put up a fight for pole position.

But unfortunately for Prancing Horse fans, this is looking more like a two-horse race between the so far evenly matched Mercedes drivers.