Red Bull's Max Verstappen completed a Friday practice double at the British Grand Prix as Mercedes' latest upgrades appeared to have little impact at Silverstone.
World championship leader Verstappen continued his imperious form to edge out Ferrari's Carlos Sainz in Practice Two by just two-hundredths of a second, with a time of 1:28.078.
Williams completed a hugely encouraging day as Alex Albon repeated his third from the opening session, with team-mate Logan Sargeant fifth behind Red Bull's Perez.
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Having struggled in Austria last weekend, Mercedes hoped that a new front wing would help push them back towards the top of the timesheet, but Lewis Hamilton could only manage 15th, with George Russell faring little better in 12th.
Completing a disappointing afternoon for the trio of British drivers racing at Silverstone, Lando Norris was 14th for McLaren.
Also on the back foot going into the weekend is Ferrari's Charles Leclerc, who missed the entire session after his car suffered an electrical issue.
Lance Stroll was sixth for Aston Martin, while team-mate Fernando Alonso only managed 10th.
Having claimed a fifth successive victory to extend his world championship lead to 81 points in Austria, Verstappen is attempting to win six races in a row for the first time in his F1 career.
Red Bull have won each of the first nine races of the season, and are looking for an 11th successive victory - stretching back to last year - that would draw them level with the record McLaren set in 1988.
Verstappen remains on top as pack shuffles behind
At a track where the RB19's dominance was expected to continue, there were no clear signs on Friday that the team's remarkable winning streak is likely to come to an end on Sunday.
Verstappen was swiftly into his rhythm once more, despite some early complaints about a lack of grip, and spent the majority of the day at the top of the timesheet.
While the Dutchman and Red Bull likely have more performance to find on Saturday, Ferrari could at least take encouragement from the narrow margin by which Sainz trailed Verstappen in Practice Two.
Any excitement at Sainz's performance will be tempered by the reliability of Leclerc's car, which will leave the Monegasque needing to display his single-lap prowess to recover on Saturday.
Even then, with the details of Leclerc's issue unconfirmed, he could face a grid penalty on Sunday if Ferrari are forced to fit a fourth control electronics unit of the season to his car.
There was hesitance to read too much into Albon finishing third in the opening session, but the fact he repeated the feat later in the day, along with Sargeant's impressive display, suggests Williams have genuine pace.
As for Mercedes, their lack of pace over one lap suggested that reaching the final part of qualifying on Saturday is far from a certainty, but there was some solace to be taken from more encouraging long-run performance.
Friday's sessions saw the debut of an updated tyre compounds provided by Pirelli, with the manufacturer making the changes to ensure safety amid higher than expected increases in downforce attained by teams during the opening months of the season.
While a practice timesheet should always be treated with caution, the topsy-turvy nature of the standings led Red Bull team principal Christian Horner to suggest that the new tyres may have played a factor in some surprise placings.
"I think these tyres are a little bit different and when you get something like that, a variable that comes in," Horner said.
"Suddenly it moves the order around and cars work slightly better than others and certain drivers adapt quicker than others. I think that is one of the variables."
Sky Sports F1's live British GP schedule (all F1 sessions on Sky Showcase)
Saturday July 8
9:15am: F3 Sprint
11:15am: British GP Practice Three (session starts 11:30am)
1:10pm: F2 Sprint
2:15pm: British GP Qualifying build-up
3pm: BRITISH GP QUALIFYING
5pm: Ted's Qualifying Notebook
Sunday July 9
8:10am: F3 Feature Race
9:50am: F2 Feature Race
11:50am: Porsche Supercup
1:30pm: Grand Prix Sunday - British GP build-up
3pm: The BRITISH GRAND PRIX
5pm: Chequered Flag: British GP reaction
6pm: Ted's Notebook
Next on the F1 calendar is the big one, Silverstone. Don't miss the British GP live on Sky Sports from July 7-9