Jenson Button admitted he had not expected Sebastian Vettel to make such a "brave" move on him for third place at the end of the Abu Dhabi Grand Prix.
The world championship leader went around the outside of Button's McLaren into Turn 11 with four laps to go.
The pass completed Vettel's charge from the tail of the field after his Red Bull was disqualified from qualifying for a fuel infringement.
"It was very brave of him," said Button. "If I'd locked up and run wide, we would've crashed.
"It was a very unusual move. I didn't expect that."
Despite being impressed with Vettel's pass, Button reckoned there was no way he could have held the Red Bull back.
Suggesting that the race's two safety cars allowed Vettel to "luck in" with his tyre strategy, Button said: "It was impossible because he was on brand new tyres and you just can't get traction with old tyres, especially old primes."
Having been very pleased with his McLaren on Friday, Button was left baffled when he struggled to sixth in qualifying. His lack of pace continued on Sunday, when his team-mate Lewis Hamilton led comfortably before retiring with a fuel pump issue.
"It was quite a fun race but at no point did I have the pace," Button said.
"I really struggled. It was very different to my Friday run. I just couldn't find the grip. It was really, really strange."
Button added: "Obviously the car is working because Lewis has been very, very quick all weekend."
McLaren now trails Ferrari by 22 points in the battle for second in the constructors' championship with two rounds to go.
"With Lewis's problem, we've lost more points to Ferrari. That's a pity," said Button. "We've just got to make sure we have two big races now."
The Briton spent some of the race pressuring Ferrari's Fernando Alonso for what would become second place, but reckoned he never had a shot at passing.
"I just couldn't get near Fernando," Button said. "I didn't have the straightline speed and traction is also an area where we're lacking."
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