Jarno Trulli, the only driver other than Michael Schumacher to have won a Grand Prix this season, has decided to leave Renault at the end of the year.
The Italian's current contract expires at the end of the season and he has been unable to agree a new deal.
The 31-year-old, who is expected to move to Toyota, hinted that he has already secured a drive for 2005.
"I am happy with this decision and feel very confident as my plans for the future are clear," he said.
Sauber's Giancarlo Fisichella is expected to replace Trulli at Renault as Fernando Alonso's team-mate.
Trulli's decision was predicted by BBC Sport at the British Grand Prix and comes after easily his best season
since graduating to Formula One in 1997.
He broke his duck in terms of pole positions and wins at Monaco and has had
the beating of highly-rated team-mate Alonso.
He made his F1 debut with Minardi in 1997 before a
mid-season switch to the now-defunct Prost team, where he stayed with only
intermittent success until 2000 when he joined Jordan.
During his Jordan years he established a reputation as a strong qualifier who struggled to keep his pace during races but since moving to Renault he has steadily overcome that perception and is now considered one of F1's top drivers.
Ralf Schumacher, who has already signed for Toyota for 2005, said on Saturday that he would like to have Trulli as a team-mate.