Jean-Eric Vergne ended the second morning of Formula 1's final pre-season test at Barcelona on top of the timesheets.
The French rookie, who had spent most of the opening day completing hard tyre runs, got a chance to lap with soft Pirelli rubber on Friday, and took his opportunity well, his 1m23.126s lap knocking Fernando Alonso's Ferrari off the top spot by 0.321s.
Vergne, who completed 31 laps during the morning, then ventured out on a set of supersofts, and had set his best first sector time of the day. His lap was ruined though when his car stopped at the uphill Turn 8 with flames pouring out, causing what was the fourth red flag of the session.
Alonso, who set his best time on hard rubber, retained second place. Nobody completed a longer stint than Alonso, whose seven-lap run on hards during the second hour featured a drop-off of around 2.5s from start to finish.
Lotus driver Romain Grosjean was third fastest, another tenth down on Alonso. He was running a programme that concentrated on set-ups and aerodynamic work.
Sebastian Vettel was fourth fastest, the Red Bull driver bringing out the fifth and final red flag of the morning when his car stopped at Turn 5 with five minutes remaining.
Fifth was Heikki Kovalainen, the Finn having recovered from food poisoning to take his place in the Caterham. His best lap came on a set of supersofts with half an hour of the morning to go, and was only 0.702s off the pace.
Next up were Force India's Nico Hulkenberg, McLaren's Lewis Hamilton and Mercedes driver Michael Schumacher, who forced two red flags. First when his car stopped at Turn 7, and then when he went off into the gravel at the left-handed Turn 5, his car needing to be retrieved.
Pastor Maldonado - the other man to cause a stoppage early on due to an issue with his engine - was ninth for Williams with Kamui Kobayashi bringing up the rear of the field for Sauber.
Due to the morning session starting late because thick fog around the Barcelona circuit, running has been extended by 30 minutes during the afternoon. The test will now finish at 17:30 local time.
Pos Driver Team Time Laps
1. Vergne Toro Rosso 1m23.126s 31
2. Alonso Ferrari 1m23.447s +0.321 35
3. Grosjean Lotus 1m23.528s +0.402 34
4. Vettel Red Bull 1m23.536s +0.410 37
5. Kovalainen Caterham 1m23.828s +0.702 34
6. Hulkenberg Force India 1m23.893s +0.767 33
7. Hamilton McLaren 1m24.111s +0.985 30
8. Schumacher Mercedes 1m24.663s +1.537 19
9. Maldonado Williams 1m25.801s +2.675 20
10. Kobayashi Sauber 1m26.111s +2.985 35