Alexander Rossi will become Formula One's first American driver since 2007 at this weekend's Singapore Airlines Singapore Grand Prix, after replacing Spaniard Roberto Merhi at the Manor Marussia team.
The tail-enders, last in the constructors' standings and yet to score a point this season, announced on Wednesday that the 23-year-old California native would drive for them alongside Britain's Will Stevens in five of the remaining seven races.
These will include the United States Grand Prix in Austin, Texas, on Oct 25.
Merhi will return for the Russian Grand Prix and the Abu Dhabi season-ender as Rossi has commitments for the GP2 race series.
The American, currently second in that series behind runaway leader Stoffel Vandoorne of Belgium, will be the first US driver on the Formula One grid since Scott Speed competed for Toro Rosso in 2007.
"I've been prepared for this opportunity for quite a while now," said Rossi, who nearly raced for Marussia in Belgium last year.
Then, the team threatened to drop Britain's Max Chilton in a contractual dispute.
The American even took part in first practice for the team in Spa last year but, by the time he had stepped out of the car, the dispute with Chilton had been resolved.
"Many will know from 2014 that the team and I already have a strong relationship and there's a bit of unfinished business for me here," he added. "This is a small F1 team that has been through so much.
"They exemplify passion and their comeback this season is extraordinary. I'm honoured to be part of this legacy and their continued growth and success."
Marussia went into administration and missed the last three races of 2014.
They returned this season only after finding a buyer at the 11th hour.
Rossi had also been linked to the US-based Haas Formula One team, who are to debut next year.
However, they recently poured cold water on his chances.
"Singapore is a circuit I really enjoy and the timing of my debut could not be more perfect. There's a lot of work ahead and I'm looking forward to a busy end to the 2015 season," he said.
Manor principal John Booth said he was delighted to give the American his chance.
"He is widely regarded as a driver who is on the cusp of an exciting F1 career and his current form in the GP2 Series has done much to reinforce his clear potential," Booth said.