Narain Karthikeyan on Thursday set a scorching pace on the first of four-day testing for Williams F1 at the Catalunya circuit in Spain.
The Indian, in only his second testing session with the British team this season, drove 97 laps and had a best timing of 1minute and 16.456 seconds, just a tenth of a second behind his teammate and race driver Nico Roseberg.
"I carried out a lot of suspension work on the FW28 today which produced some positive results. I matched the pace of the other drivers on track," said Narain.
The air temperature at the circuit remained a pleasant 17 degrees, and the sky clear and bright.
"All in all, I'm very happy with the way the test went, the car feels very comfortable now and I'm confident that we'll keep improving.
Williams' test team manager Mike Condliffe said other drivers of the team would be seen at some stage this week.
"Both (Narain and Roseberg) completed a busy testing schedule, running new aero parts and suspension items in the morning, followed by tyre construction tests in the afternoon," Condliffe said.