Timo Glock said he could do nothing to stop Lewis Hamilton from overtaking him on the final lap of the Brazilian Grand Prix, the German struggling with dry weather tyres.
The Toyota driver decided not to pit when the rain hit Interlagos with just a few laps of the race left, and the decision meant Hamilton found himself in sixth place at the start of the final lap, having been passed by Toro Rosso's Sebastian Vettel.
The Briton needed fifth to secure the crown, and he dully got it when he passed Glock on the final corner.
The German said his car was very hard to drive.
"I was on dry tyres at the end of the race when it was raining quite badly and it was just impossible on the last lap," said Glock. "I was fighting as hard as I could but it was so difficult to just keep the car on the track and I lost positions right at the end of the lap.
"Finishing in the top six is a decent result for me because I'd been struggling with the car earlier in the weekend but we were very close to fourth place so I am a bit disappointed.
"It's the end of my first season with Toyota and I'm happy with it as a whole. It was not easy for me early on but we improved the car a lot and I also improved myself during the year.
"Since Hockenheim it's been positive for me; beating my target of 20 points and finishing on the podium as well is a good achievement. Now we have to work even harder for next year to make another step forward."
Teammate Jarno Trulli finished in eighth position after he was stuck behind Giancarlo Fisichella for several laps after his first pitstop.
"It was an eventful race," said Trulli. "We had a good start and the first laps were pretty good, when I was following Felipe Massa. It started to dry up and we went for dry tyres.
"Unfortunately I got stuck behind Fisichella who was much slower than me. I didn't have the top speed to overtake him so I lost a lot of time over those laps. As soon as I got away from him I was one of the quickest on the track, I was recovering quite a lot and closing the gap to the guys in front but it was not enough.
"When it rained we took the choice to stay on dry tyres and we got a point. Having started second we missed an opportunity but overall we have done a good championship and I am pretty happy with that. Now we are aiming to make even bigger progress for next year."