Lewis Hamilton has avoided punishment for a minor rule infringement after finishing fastest in Friday's practice for the Brazilian Grand Prix.
Hamilton looked impressive in both practice sessions
Drivers are only allowed to use one set of tyres during a session and Hamilton used two in the first session.
His McLaren team were fined 15,000 euros (£10,445) and made to return one set of wet tyres for the rule break.
Honda and Super Aguri received the same punishment after Jenson Button and Takuma Sato fell foul of the same rule.
The teams were asked to return a set of tyres to ensure no advantage was gained by using part-worn tyres.
But the loss of a set of tyres may not be a great setback if a weather forecast predicting dry weather on Sunday proves to be accurate.
Hamilton explained: "We did a slow out lap on wet tyres, then came in and went out on another set.
"It was an easy mistake to make. A couple of other teams did it, yet we haven't gained anything by it. We didn't do it intentionally. There wasn't any benefit."
Maybe there's a bit too much tension in the team that has led to a silly mistake
Team boss Ron Dennis added: "It was a 100% team mistake.
"Lewis did an installation lap on one set of wet tyres and we just put on another set. It was nothing to do with Lewis.
"He only did an in-and-out lap. It wasn't as if there was any advantage, but it's clearly a breach of a rule.
"We are trying so hard and maybe there's a bit too much tension in the team that has led to a silly mistake.
"We can do no more than our best, and we are really trying hard. People make mistakes. I'm not trivialising it, but it perhaps shows we are all human.
"There's a rule there, we broke it, and now we have to get on with it."
Hamilton was fifth fastest in the first, wet session but led the way in the drier second session, ahead of McLaren team-mate Fernando Alonso.
The 22-year-old Briton leads the double world champion by four points in the race for the drivers' championship, which will be decided on Sunday, with Ferrari's Kimi Raikkonen a further three points behind.
Even Alonso admitted he wasn't too familiar with the regulation that Hamilton breached.
"I don't think we were totally aware of this rule," said the Spaniard. "I probably would have done the same thing."
Hamilton is aiming to become the sport's youngest champion as well as the first driver to win the championship in their debut season.
It was pretty evil out there in the wet
He clocked a time of one minute 12.767 seconds in the second session with Alonso managing 1:12.889.
Raikkonen had led a Ferrari one-two in the opening session ahead of Felipe Massa but Massa finished in third place ahead of his team-mate in the second session.
It was a wet start to Friday's practice at Interlagos with Hamilton opting to leave it late before heading out on to the track, while team-mate Fernando Alonso chose not to leave the pits at all.
"It was pretty evil out there in the wet," said Hamilton, who could become the first Briton to win the title since Damon Hill in 1996.
Alonso added: "We did not expect to stay wet for the rest of the weekend so we took the decision not to do any running in the morning.
There is still a lot of room for improvement on the car
"The session this afternoon was far better. I am looking forward to a competitive weekend."
The Ferraris looked good in the wet with both Raikkonen and Massa posting the fastest times.
"We are reasonably happy with the way today went," Raikkonen said. "But there is still a lot of room for improvement on the car."
"The track is great now," Massa added. "We don't have to worry about the bumps anymore. We need to congratulate those who worked on the track."
All three title challengers posted quick times during the later practice run, but it was Hamilton who proved quickest, although Alonso almost stole the lead with a fast lap with seconds remaining of the session.
If Hamilton needs an omen for the weekend, the driver who has posted the quickest practice time on Friday has subsequently won the race on 11 occasions this season.
Times after Friday's first practice session:
1. Kimi Raikkonen (Finland) Ferrari one min 19.580 secs
2. Felipe Massa (Brazil) Ferrari 1:20.062
3. Heikki Kovalainen (Finland) Renault 1:20.829
4. Nico Rosberg (Germany) Williams - Toyota 1:21.064
5. Lewis Hamilton (Britain) McLaren 1:21.121
6. Ralf Schumacher (Germany) Toyota 1:21.243
7. Sebastian Vettel (Germany) Toro Rosso - Ferrari 1:21.598
8. Mark Webber (Australia) RedBull - Renault 1:22.104
9. Jarno Trulli (Italy) Toyota 1:22.104
10. Vitantonio Liuzzi (Italy) Toro Rosso - Ferrari 1:22.250
11. Rubens Barrichello (Brazil) Honda 1:22.434
12. Jenson Button (Britain) Honda 1:22.477
13. David Coulthard (Britain) RedBull - Renault 1:22.667
14. Takuma Sato (Japan) Super Aguri - Honda 1:22.929
15. Adrian Sutil (Germany) Spyker - Ferrari 1:23.248
16. Kazuki Nakajima (Japan) Williams - Toyota 1:23.261
17. Anthony Davidson (Britain) Super Aguri - Honda 1:23.551
18. Sakon Yamamoto (Japan) Spyker - Ferrari 1:24.366
Opted out of practice: Nick Heidfeld (Germany) BMW Sauber, Robert Kubica (Poland) BMW Sauber, Fernando Alonso (Spain) McLaren, Giancarlo Fisichella (Italy) Renault
Times after Friday's second practice session:
1. Lewis Hamilton (Britain) McLaren one min 12.767 secs
2. Fernando Alonso (Spain) McLaren 1:12.889
3. Felipe Massa (Brazil) Ferrari 1:13.075
4. Kimi Raikkonen (Finland) Ferrari 1:13.112
5. Giancarlo Fisichella (Italy) Renault 1:13.549
6. Robert Kubica (Poland) BMW Sauber 1:13.587
7. Nico Rosberg (Germany) Williams - Toyota 1:13.655
8. Kazuki Nakajima (Japan) Williams - Toyota 1:33.664
9. David Coulthard (Britain) RedBull - Renault 1:13.706
10. Nick Heidfeld (Germany) BMW Sauber 1:13.785
11. Ralf Schumacher (Germany) Toyota 1:13.829
12. Heikki Kovalainen (Finland) Renault 1:13.879
13. Rubens Barrichello (Brazil) Honda 1:13.892
14. Jenson Button (Britain) Honda 1:14.095
15. Vitantonio Liuzzi (Italy) Toro Rosso - Ferrari 1:14.152
16. Jarno Trulli (Italy) Toyota 1:14.179
17. Sebastian Vettel (Germany) Toro Rosso - Ferrari 1:14.409
18. Takuma Sato (Japan) Super Aguri - Honda 1:14.431
19. Anthony Davidson (Britain) Super Aguri - Honda 1:14.477
20. Mark Webber (Australia) RedBull - Renault 1:14.543
21. Adrian Sutil (Germany) Spyker - Ferrari 1:15.095
22. Sakon Yamamoto (Japan) Spyker - Ferrari 1:15.715