Daniel Ricciardo conceded on Thursday that his Red Bull team-mate and four-time champion Sebastian Vettel may duck out of qualifying at this weekend's United States Grand Prix because of an enforced power unit change.
But, said the Australian, it was not certain this would happen and he suggested that the German was not keen to disappoint his fans back at a circuit where he was a convincing winner last year.
"I don't think it's decided finally yet, but if the power unit on his car is changed he will have to start from the pit lane and so there is not much point in fighting for pole position if that happens," said Ricciardo.
Vettel revealed his dilemma when he took part in one of the main promotional activities ahead of the race, driving his 2011 title-winning Red Bull car on the Texas streets just as this year's championship leader Lewis Hamilton was taking part in a similar stunt in New York for NBC's Today show.
Vettel, who leaves Red Bull at the end of the season, said: "We need to see, we need to confirm, but yes, we have to get an extra power unit at some stage this season -- and it's very likely it will be here."
"We had quite a bad first half of the season in terms of reliability, things happening which put us in a bad position. In practice, we'll definitely run to try to maximise the track time.
"But our focus will be more on the race because maybe qualifying for us is not that important if we have to start from the pit lane due to the regulations.... I didn't make them, but equally everyone has to respect them, and they are pretty clear."
He added that Red Bull were prepared to preserve a new power unit for the races in Brazil and Abu Dhabi.