(CNN) -- Nick Heidfeld has improved his chances of standing-in for injured Robert Kubica at Renault after he impressed in testing at Jerez, Spain on Saturday.
The German, who raced for BMW Sauber last season, went fastest of the 11 drivers in action, outpacing Ferrari's Fernando Alonso and Friday's pacesetter Michael Schumacher in the Mercedes GP.
McLaren's Lewis Hamilton was a place further back in fourth.
"I really enjoyed the day. It was fun driving the car, although it obviously takes time to get used to things when it's your first time in a car and working with a new team," Heidfeld said, BBC Sport reported.
"We had a good day, without too many problems, and luckily all the changes we made to the car went in the right direction and improved things, so I was able to push harder and harder," the German added, BBC Sport reported.
Heidfeld is a former teammate of Kubica's at BMW Sauber and his speed could put him ahead of other potential contenders for the Renault seat including former Force India driver Vitantonio Liuzzi.
Reigning world champion Sebastian Vettel finished Saturday's testing in sixth place, one place behind Sauber's Kamui Kobayashi.
Renault team boss Eric Boullier said his, and the team's first impressions of Heidfeld were "very positive," according to BBC Sport.