Romain Grosjean and Kamui Kobayashi shared top honours on the second day of F1 testing at Mugello, with the pair setting the same time after a dry day of running at the Italian circuit.

Grosjean had emerged as the man to beat during the morning session as he took over from test driver Jerome D'Ambrosio at Lotus, setting a time of 1m 21.603s that looked set to remain unbeaten as the day wore on.

Kobayashi had other ideas however, and having earlier caused a red flag when he suffered a spin, the Sauber man made the most of a soft tyre run in the closing stages of the day to match Grosjean's time and share bragging rights.

"It's always good to end the day on top, but we have to remember that in testing lap times mean very little," Grosjean admitted afterwards. "Having said that, the car felt great and I was very comfortable from the start. This test gives us an opportunity to try things that we wouldn't have time to do during a race weekend, so hopefully it'll help us to keep pushing forward.

"We've done a lot of setup work today, and for sure we'll need to take some time to look through all the data and analyse what we need to focus on tomorrow, but it's a good baseline for the final day."

Behind the top two, Sebastian Vettel was third quickest for Red Bull ahead of team-mate Mark Webber as the defending champions elected to give both drivers time on track.

Webber was out on track during the morning session before handing over to Vettel, who improved his times throughout the afternoon before eventually moving ahead of the Australian on the time-sheets.

"Unfortunately we don't have this track on the calendar," the defending champion reflected. "It's an incredible circuit with a lot of high-speed corners. It's what you hope for in a Formula One car, because you can really feel the downforce. Once you get into the rhythm it's really enjoyable.

"We've got a lot of laps to get through here. We'll be trying to sort out a lot of the items we've been testing at previous events and things we possibly want to use in the future. The really important thing from here will be the analysis after this test to see what happens to the car."

Felipe Massa completed his single day of running for Ferrari, focusing on aerodynamic component work and tyre evaluation, with the fifth quickest time at the wheel of the F2012 while Jean-Eric Vergne and Daniel Ricciardo were sixth and seventh.

As at Red Bull, Toro Rosso elected to split the day's running between its two drivers, with both setting a time within a second of the benchmark time; Vergne admitting afterwards that he felt the 65 laps completed were the 'best day's testing I've done in F1'.

Michael Schumacher was eighth for Mercedes and completed more laps than anyone else with 144, while there was encouragement for Marussia thanks to fact that Charles Pic was ninth quickest ahead of the Caterham of Vitaly Petrov.

Gary Paffett was eleventh for McLaren after a gearbox issue ended his day three hours early while Timo Glock - who took over from Pic during the afternoon - Paul di Resta and Bruno Senna rounded out the times.

"We had an extremely busy second day with Bruno completing almost our entire scheduled test programme," Williams chief operations engineer Mark Gillan said. "We evaluated a detailed aero and mechanical test matrix and have learnt a great deal. The forecast for tomorrow looks fine and we are looking forward to another productive day."

Di Resta however was restricted to just 14 laps all day for Force India as the team spent much of its time trying to resolve a hydraulic issue.

Testing concludes on Thursday.