Daniel Ricciardo ended the second day of Formula 1 testing at the top of the timesheets, but in his Toro Rosso and not a Red Bull.
The Australian was conducting an unofficial audition for a Red Bull 2014 seat in the afternoon, but despite several runs he could only get within two tenths of a second of his best Toro Rosso effort of 1m32.972 set before lunch.
He also faced the embarrassment of running off the track in to the gravel at Luffield early on during his afternoon running for Red Bull while he got used to his new surroundings.
Ricciardo's best lap time in the Red Bull was in the end only good enough for third fastest, with Carlos Sainz Jr. doing a good job on his first outing in an F1 car to set the second fastest time.
The Spaniard ended up just 0.044 seconds adrift of Ricciardo.
Behind the Red Bull and Toro Rosso drivers, Davide Valsecchi completed a programme of aerodynamic and tyre evaluation work to set the fourth fastest time, as he completed his first full day of testing for Lotus.
His induction with Lotus got off to an amusing start earlier in the day when, with his radio not working, he failed to notice for several laps that his team's pit board was indicating him to return to the garage.
This resulted in more and more desperate measures from the pit wall to get him to abort his running - until eventually an extra large makeshift 'IN' sign was finally noticed.
Oliver Turvey continued McLaren's testing programme with the fifth fastest time, while James Calado was sixth overall as he continued to learn about the Force India and help push on with the Silverstone-based team's development work.
"It was fantastic," said Calado. "Just amazing – and a fantastic opportunity. It was my dream to just get a go.
"Yesterday was more about me getting used to the sheer animal that is an F1 car, while today was more of a proper test – working on set-up and trying some things that will hopefully help."
Antonio Felix da Costa's best time from the morning, as he completed his day-and-a-half of testing before handing over to Ricciardo, was good enough for seventh overall, ahead of Davide Rigon in the Ferrari and Pastor Maldonado in the Williams.
Nico Hulkenberg completed an afternoon of tyre work for Sauber in a bid to get a better indication of the impact the new 2012 construction Pirellis will have on his team's performance. The German was 10th fastest overall with a best lap of 1m34.224s.
Will Stevens completed his first day of testing in an F1 car with the 13th fastest time for Caterham.
As well as Ricciardo's red flag, there were two other session stoppages. Robin Frijns ran off the track at Luffield just before midday during his morning of running for Sauber, while action was suspended an hour later due to debris on track.
Today's times:
Pos Driver Team Time Laps
1. Daniel Ricciardo Toro Rosso 1m32.972s 48
2. Carlos Sainz Jr. Toro Rosso 1m33.016s 39
3. Daniel Ricciardo Red Bull 1m33.187s 59
4. Davide Valsecchi Lotus 1m33.554s 91
5. Oliver Turvey McLaren 1m33.864s 97
6. James Calado Force India 1m33.957s 47
7. Antonio Felix da Costa Red Bull 1m33.958s 19
8. Davide Rigon Ferrari 1m34.053s 97
9. Pastor Maldonado Williams 1m34.116s 71
10. Nico Hulkenberg Sauber 1m34.224s 52
11. Daniel Juncadella Williams 1m34.631s 33
12. Robin Frijns Sauber 1m34.731s 17
13. Will Stevens Caterham 1m36.082s 98
14. Paul di Resta Force India 1m36.356s 41
15. Rodolfo Gonzalez Marussia 1m37.949s 92