Jenson Button believes that Daniel Ricciardo's decision to move to McLaren in 2021 will "make or break" the Aussie's career in Formula 1.
Ricciardo will head to Woking at the end of the season following a two-year stint with Renault whose results have so far fallen short of the 31-year-old driver's expectations.
Yet, Button has been impressed with Ricciardo's performance at the French squad despite the lack of significant results.
"I’m probably more impressed with what he’s done at Renault than with what he did at Red Bull," the 2009 F1 world champion told the 'In the Fast Lane' podcast.
"To have one over on Nico Hulkenberg in his first year  is very impressive."
Button admits he was among those that were puzzled by Ricciardo's decision to leave front-running team Red Bull at the end of 2018, a decision many believe was rooted in his fear of being out-staged by redoubtable teammate Max Verstappen.
"I even said to Daniel ‘I don’t get your decision to move to Renault’," said Button.
"I’m sure he’s questioned it at times, as you always do as a driver when you step backwards.
"I know he’s being paid a lot of money at Renault, but he would have also been paid a lot at Red Bull so I don’t think it’s a cash issue.
"I think it goes back to not feeling equal with your team-mate and not feeling wanted in the team, and I think that’s the reason why he made that move."
Ricciardo's transfer to McLaren, where he'll join promising talent Lando Norris, will perhaps immerse the Aussie in a more familiar anglo-saxon environment as well as provide him with a potentially championship-winning package.
Button gives the thumbs up to his friend's next big venture, but predicts a binary outcome.
"This move to McLaren, it’s make or break for his career," he said.
"He’s still young, but you’ve got to start moving towards a team that can give you race wins and hopefully fight for the Championship.
"It’s an important move for him. A McLaren with a Mercedes [engine] in the back should be very competitive."