Nick Heidfeld served notice that he is the man Lotus Renault GP needs to replace Robert Kubica by topping the timesheets at Jerez today, his first time in the R31.

It was a dream debut for the popular German, who this time last week, must have thought his F1 career was at an end. In the wake of Robert Kubica's horrific accident in a rally last Sunday, 'Quick Nick' was one of the first names mentioned in terms of a possible replacement for the Pole. However, it wasn't until Wednesday, just three days ago, that the British outfit confirmed that the German was to be given the chance to prove himself.

Letting his talent speak for itself, Heidfeld stepped up to the plate today and delivered, posting the best time of the day and missing out on the best time of the week - posted by Michael Schumacher yesterday - by just 0.009s.

In addition to sizing up Heidfeld, Lotus Renault GP evaluated a new floor upgrade today, pressure tapping and flow viz paint allowing the engineers to verify its aero characteristics. The team also ran back-to-back tests on all four Pirelli tyre compounds for the first time, confirming the different degradation rates and variations in performance.

"I really enjoyed the day," said Heidfeld. "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. 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.

"In terms of the lap times, it's very difficult for me to compare with the other teams because we don't know the fuel levels or what the others were doing," he added. "My first impressions of the car were positive, although there are always areas where you can improve."

"Today we had the chance to give Nick time in the car and we carried out a big evaluation," said Eric Boullier. "Our first feelings are very positive: he worked well with the team, gave good feedback and improved the car during the day. 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."

"The day was based around getting Nick comfortable in the car and giving him as much mileage as possible," added Alan Permane. "He adapted to the car and the systems quickly. We played around with the set-up early on and changed a few things during the day, this included the weight distribution and the toes and cambers for the Pirelli tyres. Unfortunately the afternoon was disrupted by several red flags, so we were not able to complete the long runs we had planned."

While Heidfeld topped the timesheets, there is no doubt as to who the star of the show was today, certainly as far as the crowds were concerned. The locals turned out in the thousands to watch Fernando Alonso, indeed, such were the numbers one would be forgiven for thinking that a fully fledged Grand Prix was taking place.

Despite the huge traffic jams outside as thousands more fans made their way to the track to watch Alonso begin his second season with Ferrari, those inside weren't disappointed as the Spaniard completed 131 laps and finished second quickest.

The two-time world champion worked through a similar programme to the one that team-mate Felipe Massa completed yesterday. Running with an image of Robert Kubica's helmet on his own, in the morning he worked on a comparison between the four types of tyre that Pirelli had brought here. Then, in the afternoon, he concentrated on a long run.