Lewis Hamilton hopes Jenson Button stands in for Fernando Alonso when the McLaren driver skips Formula 1's Monaco Grand Prix to race in the Indianapolis 500.
News broke this week of Alonso's shock decision to miss the most famous race on the F1 calendar to make his IndyCar debut next month in a McLaren-entered car run by the Honda-powered Andretti Autosport team.
While Button, who remains contracted to McLaren after making way for Stoffel Vandoorne to partner Alonso in F1 this year, is understood to be the preferred option for the seat, so far the team says it does not have a replacement firmed up for Monaco.
Alonso is modern IndyCar's Mansell moment
"I hope Jenson comes back, it would be great for the sport to have Jenson back," said Hamilton, who raced alongside Button at McLaren from 2010-12.
"I still think he is one of the best drivers, his calibre is very high, and he is experienced."
Hamilton added that he would never skip a grand prix to race elsewhere, but he supported Alonso's decision and believes F1 drivers should take in other events where possible.
"Firstly it is great that a driver is able to do it, we should be allowed to do more than one series," he said.
"There was a time when drivers could do multiple series so it is pretty cool.
"I wouldn't want to miss out any races in F1, you need to do all the races.
"I would like to do MotoGP, I'd love to ride a MotoGP bike - or a NASCAR race, like the Daytona 500."
Hamilton said he will watch on with interest to see how Alonso deals with the challenge of learning about oval racing in the short preparation time he will have.
"It is a completely different character [of racing], it is a lot, lot different," he said.
"The set-up, the banking, how much you lift, how much you use the tyres - it's definitely a lot to learn in a short space of time.
"But Fernando is one of the best drivers in the world.
"He will be the best driver in the paddock [at Indy] but he does not have the most experience, so it will be interesting to see how he copes without that experience."