Nico Muller topped the times for Trident Racing on the opening day of GP3 testing at Estoril on Tuesday.
The 19-year-old Swiss, who has yet to secure a race deal for the coming season, lapped the Portuguese circuit in 1m31.285s with just 15 minutes of the afternoon session remaining, knocking Mitch Evans off the top spot by just 0.015sec.
Evans had set the fastest time during the morning session, despite the MW Arden driver completing only seven laps before the midday break. He improved by just 0.071sec during the warmer afternoon.
Antonio Felix da Costa was third quickest for Carlin to make it three GP3 race winners in the top three positions. Lotus pair Aaro Vainio and American Conor Daly completed the top five ahead of MW Arden's Matias Laine.
New Manor signing Tio Ellinas was seventh quickest with Tamas Pal Kiss (Atech CRS), David Fumanelli (MW Arden) and 15-year-old Matheo Tuscher (Jenzer) completing the top 10.
Manor driver Fabiano Machado brought out the red flags during the morning with a spin into the gravel, while Carlin's Will Buller did likewise during the afternoon. They were 14th and 17th overall.
The test continues on Wednesday.
Combined times:
Pos Driver Team Time Laps
1. Nico Muller Trident Racing 1:31.285 52
2. Mitch Evans MW Arden 1:31.300 23
3. Antonio F. da Costa Carlin 1:31.361 42
4. Aaro Vainio Lotus GP 1:31.461 40
5. Conor Daly Lotus GP 1:31.487 48
6. Matias Laine MW Arden 1:31.498 31
7. Tio Ellinas Manor Racing 1:31.640 45
8. Tamas Pal Kiss Atech CRS GP 1:31.713 21
9. David Fumanelli MW Arden 1:31.745 42
10. Matheo Tuscher Jenzer Motorsport 1:31.867 54
11. Alexander Sims Status GP 1:31.941 53
12. Robert Visoiu Jenzer Motorsport 1:32.043 56
13. Daniel Abt Lotus GP 1:32.089 42
14. Fabiano Machado Manor Racing 1:32.203 74
15. Marlon Stockinger Status GP 1:32.240 35
16. Miki Weckstrom Status GP 1:32.252 35
17. Will Buller Carlin 1:32.677 42
18. Dmitry Suranovich Manor Racing 1:32.831 49
19. Antonio Spavone Trident Racing 1:32.849 53
20. Patric Niederhauser Jenzer Motorsport 1:32.977 58
21. Alex Brundle Carlin 1:32.993 40
22. Vicky Piria Trident Racing 1:33.383 36
23. Ethan Ringel Atech CRS GP 1:33.535 50
24. Robert Cregan Tech 1 Racing 1:33.911 43
25. Yuki Shiraishi Tech 1 Racing 1:35.125 29