Valtteri Bottas outpaced the returning Lewis Hamilton at the end of the final Friday practice session of the 2020 season for the Abu Dhabi GP, in a session disrupted by a fire on Kimi Raikkonen's Alfa Romeo car.
Bottas, who endured a difficult Sakhir GP last week alongside George Russell, who starred as stand-in for Hamilton, set the pace from his usual Mercedes team-mate by 0.203s with a best lap under the Yas Marina floodlights of 1:36.276.
Red Bull's Max Verstappen was third, 0.8s off the leading Mercedes pace.
However, less could be read into ultimate performance than normal as, unusually, none of the top three completed uninterrupted qualifying simulations. Hamilton and Verstappen had lap times deleted for exceeding track limits, while Bottas ran wide at Turn One on what should have been his own quickest effort.
Hamilton said he had felt "super excited" for his return after missing last weekend's race and said of his Friday: "It definitely took me a minute to get back used to it for the first session, and in the second one I think I was still getting my bearings. But not too bad."
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All teams then faced further disruptions during their race simulations when the red flag was thrown with 20 minutes to go when the rear of Raikkonen's car caught fire and the Finn had to pull off the track.
Marshals quickly put out the flames before Raikkonen, who had quickly exited the burning car, took over the extinguisher himself and added some finishing touches, aware of key areas of the internals the team would not want to be burnt.
Moments earlier and Russell's Mercedes-engined Williams had also been emanating smoke, ending the Briton's session early with the team quickly getting to work on the FW43.
With teams running used engines for Friday's session, the power units were at the end of their mileage lives after a 17-race campaign in which power unit allocations are restricted on cost grounds.
"Of course that's not ideal, but at least it happened to an engine and gearbox we were going to change in any case," said Raikkonen. "It's obviously a lot of work for the guys in the garage but we should be ok for tomorrow."
Who's holding the early pace edge?
Mercedes did nonetheless appear to have an edge on Red Bull, with Hamilton quickly back in the groove after missing the first grand prix of his career last week due to coronavirus.
"He looks fit, and in a good place, like it never happened," said Mercedes boss Toto Wolff to Sky F1. "But I guess it was a hard week."
While the season's top two teams are likely to dominate the season's final weekend in normal conditions, the battle behind them looked incredibly close on Friday's evidence.
McLaren's Lando Norris took fifth but lapped only 0.178s faster than 12th-placed team-mate Carlos Sainz, with five teams covered by the smallest of margins around the 5.55km circuit.
Sergio Perez, last week's maiden race winner, was right in that pack in seventh place but the Mexican's final race for Racing Point on Sunday will start from the back of the grid owing to engine change penalties. Haas' Kevin Magnussen, 16th quickest at the start of his final weekend in F1, also has power-unit penalties to take and will join Perez on row 10.