ART Grand Prix driver Conor Daly set the pace as GP3's latest pre-season test got underway at Barcelona.
The American's lap of 1m34.578 came with just 10 minutes of the day's running to go and knocked Manor driver Tio Ellinas off the top spot by 0.132 seconds.
Daly, who has not yet committed to a race programme for the coming season, said: "We had a lot to figure out with the new GP3/13 car at the first test in Estoril and I believe now we have found a great set-up and a nice balance to achieve that one important hot lap.
"I am extremely happy and it was a nice surprise to be P1.
"I feel really positive about the second-generation car, it's much more fun to drive and certainly makes you question yourself before you add more power. I love having more speed!"
Toyota Racing Series champion Nick Cassidy, having his first run-out with Manor, set the pace during a morning that featured intermittent showers and left drivers teetering around on a damp surface using slick tyres.
Cassidy, who was pushed closest by Kevin Korjus and Estoril pacesetter Carlos Sainz Jr during the morning, improved his time by over a tenth in the afternoon, but still fell to third overall.
The final 30 minutes of track action was dominated by drivers undertaking qualifying simulations on fresh tyres.
Jenzer driver Alex Fontana, Carlin's Nick Yelloly and Daly's ART team-mate Facu Regalia were among them, and completed the top six.
David Fumanelli, seventh overall for Trident, was the only driver to bring out the red flags, the Italian twice stopping with technical problems.
Pos Driver Team Time Gap Laps
1. Nick Cassidy Manor 1m34.924s 21
2. Kevin Korjus Koiranen 1m35.196s + 0.272s 19
3. Carlos Sainz Jr MW Arden 1m35.261s + 0.337s 22
4. Alex Fontana Jenzer 1m35.350s + 0.426s 26
5. Tio Ellinas Manor 1m35.436s + 0.512s 19
6. Aaro Vainio Koiranen 1m35.661s + 0.737s 28
7. Lewis Williamson Bamboo 1m35.711s + 0.787s 25
8. Patric Niederhauser Jenzer 1m35.722s + 0.798s 19
9. Adderly Fong Status 1m35.820s + 0.896s 25
10. Facu Regalia ART 1m35.845s + 0.921s 14
11. Nick Yelloly Carlin 1m35.878s + 0.954s 16
12. Patrick Kujala Koiranen 1m35.910s + 0.986s 18
13. Conor Daly ART 1m35.934s + 1.010s 14
14. David Fumanelli Trident 1m36.045s + 1.121s 18
15. Jack Harvey ART 1m36.156s + 1.232s 12
16. Daniil Kvyat MW Arden 1m36.163s + 1.239s 14
17. Dino Zamparelli Manor 1m36.354s + 1.430s 23
18. Josh Webster Status 1m36.520s + 1.596s 23
19. Emanuele Zonzini Trident 1m36.622s + 1.698s 14
20. Giovanni Venturini Trident 1m36.783s + 1.859s 18
21. Robert Visoiu MW Arden 1m36.827s + 1.903s 20
22. Jimmy Eriksson Status 1m37.049s + 2.125s 17
23. Luis Sa Silva Carlin 1m37.175s + 2.251s 19
24. Eric Lichtenstein Carlin 1m37.747s + 2.823s 20
25. Samin Gomez Jenzer 1m37.877s + 2.953s 23
26. Ryan Cullen Bamboo 1m38.058s + 3.134s 17
27. Carmen Jorda Bamboo 1m39.522s + 4.598s 16
Pos Driver Team Time Gap Laps
1. Conor Daly ART 1m34.578s 28
2. Tio Ellinas Manor 1m34.710s + 0.132s 27
3. Nick Cassidy Manor 1m34.715s + 0.137s 23
4. Alex Fontana Jenzer 1m34.826s + 0.248s 30
5. Nick Yelloly Carlin 1m34.900s + 0.322s 39
6. Facu Regalia ART 1m34.943s + 0.365s 27
7. David Fumanelli Trident 1m35.059s + 0.481s 32
8. Daniil Kvyat MW Arden 1m35.171s + 0.593s 32
9. Carlos Sainz Jr MW Arden 1m35.218s + 0.640s 36
10. Kevin Korjus Koiranen 1m35.313s + 0.735s 43
11. Jimmy Eriksson Status 1m35.337s + 0.759s 34
12. Jack Harvey ART 1m35.402s + 0.824s 28
13. Emanuele Zonzini Trident 1m35.448s + 0.870s 23
14. Patric Niederhauser Jenzer 1m35.593s + 1.015s 19
15. Lewis Williamson Bamboo 1m35.604s + 1.026s 30
16. Giovanni Venturini Trident 1m35.651s + 1.073s 33
17. Dino Zamparelli Manor 1m35.716s + 1.138s 32
18. Adderly Fong Status 1m35.759s + 1.181s 40
19. Robert Visoiu MW Arden 1m35.934s + 1.356s 33
20. Aaro Vainio Koiranen 1m35.967s + 1.389s 39
21. Luis Sa Silva Carlin 1m36.277s + 1.699s 34
22. Josh Webster Status 1m36.424s + 1.846s 10
23. Samin Gomez Jenzer 1m36.485s + 1.907s 36
24. Eric Lichtenstein Carlin 1m36.572s + 1.994s 44
25. Ryan Cullen Bamboo 1m37.909s + 3.331s 24
26. Patrick Kujala Koiranen 1m37.955s + 3.377s 12
27. Carmen Jorda Bamboo 1m38.683s + 4.105s 43