Mark Webber has questioned Jenson Button's commitment to his F1 return at Monaco.
The Briton, who was revealed as being part of McLaren's "innovative three driver strategy" for 2016, effectively drove his last ever F1 race at Abi Dhabi last season.
However, in the wake of the move that sees Fernando Alonso skip the Monaco Grand Prix for the Indy 500, the 2009 world champion has been brought out of 'retirement' to replace the Spaniard.
Though he hasn't spoken to Button about the move, Webber has serious doubts about the Briton's commitment.
"It's a non-story, Jenson at Monaco," her told Speed Week. "He goes out, has fuel pressure problems in FP1, qualifies 17th, retires on lap 12. Whatever, who cares?
"Jenson didn't do any testing in Bahrain, he doesn't take it so seriously," he continued. "'I want to stay in America and do my triathlon, I'm not bothered about the Bahrain test'... which for me was a surprise. The first session in Monaco will be 'wakey-wakey'. I don't think he's very interested."
"I don't think he would have been first on the phone," he added, in terms of the Briton volunteering his services.
Though dubious about Button, the Australian has no doubts about teammate Stoffel Vandoorne.
"I like Stoffel a lot, he's got his head screwed on," he said. "He sees the big picture quite nicely for his age, he has a very good career in front of him.
"This is a good learning process for him in this car, with Fernando in the other garage. Fernando is running the team at the moment, he's running McLaren. Fernando is colossal, mercurial. So for Stoffel, it's good learning."