MANAMA Britain's Jenson Button will stand in for Fernando Alonso at next month's Monaco Formula One Grand Prix while the Spaniard competes in the Indianapolis 500 on the same day, McLaren announced on Friday.
"I'm thrilled to be making a one-off return to Formula One racing, and I couldn't think of a better place to make that return than my adopted home Grand Prix: Monaco," the 37-year-old said in a statement at the Bahrain Grand Prix.
Monaco resident Button handed over his McLaren seat to Belgian rookie Stoffel Vandoorne at the end of last season but remained under contract to the team with the possibility of returning in 2018.
He won the showcase race in 2009 on his way to the title with Brawn GP.
Honda-powered McLaren have endured a tough start to the season, with no points from two races, but Monaco's tricky street circuit could suit their car better and is also one where drivers can make the difference.
Button will be the most experienced driver in the race as he makes his 306th start, with the Briton third in the all-time list behind the retired Rubens Barrichello and Michael Schumacher.
He is also the last driver to win a race for McLaren, in Brazil in 2012, but cannot hope for such success this time.
"It's one of my all-time favourite racetracks," said the winner of 15 grands prix who made his Formula One debut 17 years ago with Williams.
"OK, I realise we won't have a realistic chance of repeating my 2009 victory, but I think we'll have an opportunity to score world championship points, which will be very valuable to the team in terms of constructors' rankings.
"As for Fernando, I hope he not only fares well at Indy but enjoys it too."
McLaren announced earlier in the week that double world champion Alonso would compete at Indianapolis with a car run by Andretti Autosport, last year's winners.
McLaren racing director Eric Boullier said Button, who has kept his fitness up by competing in triathlons, would spend time in the team's simulator but there was no need for him to join an in-season test in Bahrain next week.
"I rang him and his first reaction was, 'Great, I'm so excited," said the Frenchman of their short conversation after initial text exchanges. "You could feel the excitement on the phone was real.
"Jenson was the choice from day one, the obvious choice by far," he told reporters. "I can guarantee that by lap 10 in first practice he will be OK."
(Editing by Sudipto Ganguly and Ken Ferris)