Jordan enjoys promising Friday

Heidfeld ended the day 14th fastest, one spot ahead of Friday tester Glock. The team's other race team driver, Giorgio Pantano, was 19th fastest.

"It was a good day for us because we didn't have any technical problems and that allowed us to do a lot of laps," said Heidfeld. "It was also very productive for us in terms of trying various things on the car. Plus, in terms of our positions on the timing charts it's a better Friday for us."

Glock said: "I did some tyre comparisons and it was interesting to see the difference between the two sessions as the feel was completely different in the afternoon, which makes it a little bit difficult to choose the right tyre. We will have to look at the information and discuss with the other drivers' feedback."

Pantano added: "This afternoon we found our tyre comparison work a little bit strange given the changing grip conditions. We need to understand why this was so we can decide the limits of our car and tyre package at this track and which way to go for the race."