Lewis Hamilton and Valtteri Bottas cannot explain their lack of improvement at the end of Formula 1 Spanish Grand Prix qualifying, with polesitter Hamilton calling his final lap "really poor".
The Mercedes drivers locked out the front row for the fourth time in the 2020 season, with Max Verstappen continuing what he called his "subscription" to third place, in qualifying at Barcelona on Saturday.
But all three - along with Racing Point's Lance Stroll - did not go quicker on their final laps on the soft tyre in Q3 compared to the other six runners, despite Hamilton calling his 1m15.584s lap that ended up as the pole-winning time "solid" with places he "felt like I could improve".
When asked by Autosport to explain why he did not go faster on his final lap, Hamilton said: "Not really sure.
"This track, there is track ramp and then the track temperature can vary and the wind can vary.
"The first lap felt OK, but a little bit - in some areas - within the limit so I knew that there was some areas that I could improve on.
"And then on the next run the tyres just didn't feel the same and the grip wasn't the same for me.
"So it was just overall a really poor second lap - I kept going, but it was nowhere near as good as the first one."
Bottas set the fastest time in the second sector on his final run, but he ended up slower than his initial Q3 attempt after a poor end to the lap.
"I don't think conditions really changed - at least it felt like they didn't really improve for the second run," he said of his last effort.
"I thought I was going to improve because when I crossed the line I was one tenth up from my previous time, but then obviously it went to zero, so maybe I just had a bit more distance - that's how the time delta works."
Hamilton also explained that he "made some really good changes and progressed forwards" during the overnight analysis following Friday practice, which led to him topping FP3 and then taking his 92nd F1 pole and 150th front row start.
"Each first lap [in every qualifying segment] was strong, which I was really happy with," he said.
"The one in Q3 was solid. I felt like I could improve, but I wasn't able to do it on the second lap [and] fortunately neither could the strong dude next to me!
"He's keeping me honest, it's obviously very close between us, so every millisecond counts."