Lewis Hamilton wants McLaren to appoint Jenson Button as Fernando Alonso's replacement for the Monaco GP.
Alonso will miss the race to take part in the Indianapolis 500 and McLaren are yet to confirm who will take the Spaniard's place.
Alonso to miss Monaco for the Indy 500
But Button, who stood down from a race seat with the team at the end of last season, is the obvious choice and remains under contract with McLaren.
"I hope Jenson comes back. I think it would be great for the sport to have Jenson back in," said Hamilton, a former team-mate of Button for three seasons between 2010 and 2012.
"I still think he is one of the best drivers. His calibre is higher than any other driver who could take that spot - his calibre and experience."
Button hasn't driven competitively since his swansong race in the 2016-season finale at Abu Dhabi in November. But a two-day test will be staged in Bahrain immediately after this week's grand prix in the desert, offering an immediate opportunity for McLaren to bed-in Alonso's stand-in.
Asked whether Button's level of fitness was likely to be an issue if he did return, Stoffel Vandoorne told Sky F1: "He'll have only missed four races if he does jump in so l don't see it as an issue."
An announcement from McLaren on the identity of Alonso's replacement is expected imminently.
But when the team confirmed at September's Italian GP that Button wouldn't be racing in 2017, then-team boss Ron Dennis said: "Jenson will be in the simulator, he will attend some races and he is contracted to race if needed."
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