Who is sweating on an F1 2017 drive?

Felipe Massa's decision to retire from Formula 1 at the end of this season, and Jenson Button's choice to step back for at least a year and sort of 'see how it goes', means the final pieces of this year's driver-market jigsaw should start falling into place.

McLaren-Honda has solved its conundrum by promoting 2015 GP2 champion Stoffel Vandoorne into a race seat alongside Fernando Alonso, but retaining Button as its F1 reserve and ambassador.

That neat Ron Dennis parlour trick takes both drivers off the market, meaning Williams now cannot replace Massa with Button (as it was hoping to do at one stage), while Renault will also definitely not get its mitts on Vandoorne - a driver whom at one point it hoped to sign on a loan arrangement with McLaren.

It also looks likely that Renault will miss out on snapping up Sergio Perez and his Mexican backers. There has been enormous confusion over this situation since Force India team owner Vijay Mallya declared it was a done deal during the British Grand Prix in July, only for Perez to claim otherwise.

Perez's deals are structured in two stages, whereby he secures a certain portion of financial support himself then signs with a team, before his major supporters make separate commercial arrangements of their own with said team. It appears there is still some haggling to be done with those backers, but nevertheless not much chance of Perez jumping ship.

You could argue this either way from Perez's point of view. Renault is the only works team left on the grid with seats available, and has more potential to grow than Force India does; but that growth is not the work of a moment, and in terms of immediate form and results Force India currently looks the best place to be outside the 'big four' of Mercedes, Ferrari, Red Bull and McLaren-Honda.

With Massa stepping down we can safely assume that Williams plans to renew terms with incumbent Valtteri Bottas, a driver in whom it has invested much over the years and who has impressively raised his game as this season has worn on.

He might not be flavour of the month with Ferrari any longer, but Bottas has driven well this year and is most definitely worth keeping around from Williams's point of view.

But that could also make him a target for Renault. In terms of results and experience he is not too far behind Perez, and if there is interest there, the Bottas camp could well view Renault as a better longer-term option for his career.

Should Bottas stay put it would appear Williams faces a straight choice between development driver Lance Stroll and Sauber's Felipe Nasr for the other seat. Both drivers come with commercial support, which is an important consideration for a team with financial holes to fill, but it looks as though Stroll's pockets are deeper and that has to make him the favourite.

He is probably not quite ready for F1 yet, even though he is likely to win the FIA's European Formula 3 Championship and has been racking up mileage in a 2014-spec Williams to prepare himself for the step up.

A year in GP2 while gaining free-practice mileage and knowledge as a reserve makes the most sense in my mind, even though I'm told he's keen to make a Max Verstappen-style leap now.

For Nasr, the best bet is probably remaining with Sauber for another season, now that the team has secured fresh financial backing and begun hiring new staff again. But, fairly or not, that seat will always come with a 'but isn't it just Marcus Ericsson's team now?' tag, and rumour has it Manor is quite interested, so Nasr may have another option.

To a certain degree, Manor's Pascal Wehrlein is a potential big player here, should Mercedes wish to see him step up after a strong rookie year and give him a chance to impress in a more competitive midfield car.

As well as being a clearly capable driver, he affords Mercedes' customers the attractive opportunity to offset engine costs. Much depends on Mercedes' evolving relationship with Manor, and whether Mercedes would prefer to keep him there for a second season. But Wehrlein surely also represents a viable Plan B for Williams and Force India.

Renault is arguably the biggest player left in the market. Whether or not it succeeds in prising Perez from Force India, somehow convincing Red Bull to loan Carlos Sainz Jr from Toro Rosso, or stealing away Williams incumbent Bottas, its two current drivers are under pressure.

Renault is clearly very keen on 2014 Euro F3 and '15 GP3 champion Esteban Ocon, and there's every chance that, with Mercedes' blessing, it will give him a shot next season, so long as he does enough during his nine-race stint with Manor to prove he's got what it takes.

One gets the feeling Renault will stick with an unchanged line-up for next year only if it ends up with Hobson's choice. That means Kevin Magnussen and Jolyon Palmer are probably competing for one available seat, if they are not frozen out altogether.

Magnussen is probably the favourite here. He has the greater experience, has generally been quicker, and achieved the higher peaks during a tough season. He's maybe not done quite as well as hoped given the opportunity to resurrect his career, and comments from Renault management about lacking leadership within the driver line-up are telling. But team-mate Palmer, though improved, has probably not done quite enough to extend his stay beyond a single season.

Should Renault somehow strike a deal to take Sainz from Toro Rosso that could be the saving of Daniil Kvyat's ailing F1 career.

The Russian has gone into near freefall since losing his Red Bull seat to Verstappen in May. He has steadily begun to gather himself together, but improved performances have sadly started to come just as Toro Rosso has really felt the pinch of using that outdated Ferrari engine.

Suggestions that Red Bull's GP2 points leader Pierre Gasly could replace Kvyat before the end of the season, later denied by both Gasly and Red Bull motorsport boss Helmut Marko, only pile more pressure on Kvyat's overburdened shoulders.

Red Bull seems prepared to be unusually patient with Kvyat, but he needs to start proving that he's really worth all the trouble.

The junior team model is becoming more apparent in F1 now. It appears both Mercedes and Ferrari are catching on to Red Bull's drift. Mercedes has got into bed with Manor, while Ferrari has very close links with Haas.

Haas looks certain to retain Romain Grosjean for a second season. Beyond the fact that he's bagged all of those precious championship points himself, the team also says signing him has allowed it to attract a higher quality of staff to its fledgling operation than otherwise might have been possible.

Team-mate Esteban Gutierrez is there because of his Ferrari links, and has done a solid job returning to full-time action after a year out. But the jury is out as to whether he's really done quite enough to warrant a contract extension. There have been flashes of real speed, and he's compared pretty favourably against a driver as highly rated as Grosjean, but still hasn't been able to score a point, or really string a weekend together.

At Monza he blew a brilliant qualifying performance with a poor start that team boss Gunther Steiner suggested was all down to the driver not dealing so well with the pressure of expectation. Gutierrez could be under even more pressure with Charles Leclerc looking set to win GP3 and impressing on Friday runouts with Haas.

Of the remaining players in the driver market, Gutierrez, Magnussen, Palmer and Kvyat look most vulnerable.