Nick Heidfeld looks set to slide into injured Robert Kubica's seat at Renault after impressing during the last round of testing at Jerez this weekend.
Team principal Eric Boullier praised Heidfeld's contribution and said that Renault had been closely assessing his performance.
"We had the chance to give Nick time in the car and we carried out a big evaluation," said Boullier. "Our first feelings are very positive: he worked well with the team, gave good feedback and improved the car during the day."
Boullier also praised Robert Kubica and Vitaly Petrov's earlier work on the 2011 Renault, saying: "We managed to cover 86 laps and the times are encouraging, which is also thanks to Robert and Vitaly's early feedback and the hard work of everybody in the team."
If further proof were needed that the vacant seat is Heidfeld's to lose, Renault's official reserve driver Bruno Senna appears to have ruled himself out of the reckoning.
"I only had one day in the car and it was good, but for preparation you need much more than that - they need a driver that's ready to do it," said the Brazilian.
The other names that could step in at the last minute include Pedro de la Rosa and Vitantonio Liuzzi.