Lewis Hamilton has set a stunning pace on the penultimate day of pre-season testing at the Circuit de Catalunya.
The Mercedes driver set a lap of one minute 20.558 seconds - the fastest time of the winter so far and 1.069 seconds clear of the field on Saturday.
Force India's Adrian Sutil was second fastest, just 0.046secs ahead of Ferrari's Felipe Massa in Barcelona.
Hamilton admits that he is being careful with his predictions about his team's pace.
He told BBC Sport at this test: "Last season in Japan we were two seconds off the McLaren I was driving and Red Bull and in the last race in qualifying it was 0.9secs.
"McLaren have probably added a second or a second or a half, so that's 2.5 to three seconds the team has had to gain in the same period.
"You have to weigh it all up and think that's possibly not achievable but the guys have given it their best shot. To build them up and then disappoint them, I don't want that to happen. And then anything positive that happens is just going to be a bonus."
Lap times in testing are notoriously poor indicators of true form for the season ahead, but there is no doubt that Hamilton's performance was impressive.
No other team has conclusively proved it can do that sort of time - although given an understanding of how teams run their winter programmes and from looking at the cars on track it seems likely that Red Bull, Lotus and Ferrari and probably McLaren, too, are similarly competitive.
After Friday's testing, Hamilton's former McLaren team-mate Jenson Button said: "I really don't know who's quick but the one team that has been consistently quick has been Mercedes more than anyone else."
The Force India of Adrian Sutil was second fastest, ahead of Ferrari's Felipe Massa and Pastor Maldonado's Williams.
Both the Ferrari and the Williams had significant updates on them, the Ferrari on the front wing and exhaust/rear bodywork and Williams with a Red Bull-style rear bodywork design.
Sauber's Esteban Gutierrez was fifth ahead of Sergio Perez's McLaren, Red Bull's Mark Webber, using a new front wing, Toro Rosso's Jean-Eric Vergne and the Lotus of Italian Davide Valsecchi.
Valsecchi was drafted in as a late replacement for Kimi Raikkonen, who is suffering from a stomach upset.
The team's other race driver, Romain Grosjean, is flying back from Paris to Barcelona to take over the car in the afternoon.
Frenchman Jules Bianchi had his first run in the Marussia after signing as a late replacement for Brazilian Luiz Razia, dropped following a dispute over sponsorship payments.
Bianchi impressed with the ninth fastest time, 0.8secs faster than his team-mate Max Chilton had managed so far at this track this winter. He was also faster than Giedo van der Garde's Caterham, the team's back-of-the-grid rivals.
FINAL PRE-SEASON TEST, CIRCUIT DE CATALUNYA, DAY THREE MORNING, FASTEST TIMES
1. Lewis Hamilton (GB) Mercedes 1:20.558
2. Adrian Sutil (Ger) Force India-Mercedes 1:21.627
3. Felipe Massa (Brz) Ferrari 1:21.673
4. Pastor Maldonado (Ven) Williams-Renault 1:22.305
5. Esteban Gutierrez (Mex) Sauber-Ferrari 1:22.553
6. Sergio Perez (Mex) McLaren-Mercedes 1:22.694
7. Mark Webber (Aus) Red Bull-Renault 1:23.116
8. Jean-Eric Vergne (Fra) Toro Rosso-Ferrari 1:23.223
9. Davide Valsecchi (Ita) Lotus-Renault 1:23.448
10. Jules Bianchi (Fra) Marussia-Cosworth 1:24.307
11. Giedo van der Garde (Ned) Caterham-Renault 1:24.520