Max Verstappen put himself on 'provisional pole' ahead of a potential qualifying washout for this weekend's Styrian Grand Prix.
The session at the Red Bull Ring was more captivating than a normal FP2 given the significant threat of thunderstorms for the area on Saturday, and the prospect of qualifying not taking place either on Saturday, or even potentially Sunday morning as a back-up.
Ordinarily in FP2, the drivers post quick laps early on before embarking on race runs over the second half of the 90-minute programme, but most drivers were still taking to soft tyres in the closing half-hour on the basis their times from the session could ultimately lead to the grid formation.
Red Bull driver Verstappen emerged with the quickest lap on Pirelli's soft tyres, posting a time of one minute 03.660secs.
As an indicator as to the serious nature of the session, the Dutchman's time was just under two-tenths of a second slower than his hot lap in the final period of qualifying for last weekend's season-opening Austrian Grand Prix.
If Verstappen is on pole, Mercedes' Valtteri Bottas will join him on the front row of the grid after finishing 0.043s adrift, with the line-up the reverse of the way the duo started on Sunday.
Racing Point certainly threw their weight behind the session as Sergio Perez and Lance Stroll used numerous sets of soft tyres, with the Mexican third quickest, 0.217s behind Verstappen, with Stroll half-a-second off the pace in fourth.
McLaren's Carlos Sainz was almost seven-tenths of a second down, followed by Lewis Hamilton in his Mercedes. The six-time F1 champion, who was quickest in all three practice sessions last week, did not enjoy the cleanest of sessions.
Mercedes confirmed that "Lewis isn't happy with the car, as can be seen from the gap to the front on a single lap.
"We completed a set down in the garage to check what we can in session in terms of alignments etc." The team is to "investigate more thoroughly this evening".
With the cars struggling for grip in the hot conditions, with an air temperature of 30 degrees centigrade and track temperature over 50, Red Bull's Alex Albon suffered two spins, one late on into the gravel on hard tyres.
Albon eventually finished seventh fastest, 0.777s behind team-mate Verstappen, with McLaren's Lando Norris the only other driver within a second of the leader. Norris faces a three-place grid drop for the race.
Ferrari's Charles Leclerc and Renault's Esteban Ocon rounded out the top 10, both just over a second back, with Sebastian Vettel 16th and nearly two seconds down in his SF1000.
Daniel Ricciardo will be praying there is a qualifying session after enduring a heavy crash after 15 minutes, bringing out a red flag.
Ricciardo had only completed two installation laps when he lost control of his Renault on the entry into the right-hander at turn nine, smacking into a barrier after careering backwards across a gravel trap.
Although Ricciardo could be seen limping upon exiting the car, and on his return to the paddock, he has been declared fit by the FIA medical delegate.
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