Grosjean puts Lotus top on second morning of F1 testing at Mugello

In contrast to the torrential weather which blighted the opening day, conditions were dry almost from the outset, allowing teams the chance to catch up with their disrupted programmes.

Many therefore opted to run with periscope gauges or various aero sensors rather than chase times.

Such priorities would not diminish Grosjean's pace, however, as he pulled clear of the field after barely an hour in and never looked under threat thereafter. He ended the morning on a 1m21.603s.

Mark Webber, in the Red Bull for this morning before handing over to reigning champion Sebastian Vettel for the final day and a half, ended the morning as Grosjean's nearest challenger.

Webber had run second for much of the morning, still more than 1.5s adrift of the Frenchman, but in the final hour a medium-tyre run allowed him to close to within four tenths. The pair were the only two to dip below the 1m22s mark.

Felipe Massa kept Ferrari near the top by going third fastest, despite a programme which saw him make several low speed runs early on and run with a periscope gauge attached to his roll hoop for almost the duration.

Toro Rosso's Jean-Eric Vergne ended fourth ahead of Sauber's Kamui Kobayashi and Mercedes' Michael Schumacher, with the German managing 74 laps, the most of any driver.

That was in stark contrast to Paul di Resta, who managed just seven laps and failed to set a time in the Force India. The team said an issue with the hydraulics was the most likely cause of its woes, but it remains optimistic of running before the end of the day.

The Scot propped up the timesheets as a result, separated from Schumacher by Charles Pic (Marussia), Vitaly Petrov (Caterham), Gary Paffett (McLaren) and Bruno Senna (Williams).

Pos  Driver                 Team                    Time     
 1.  Romain Grosjean        Lotus-Renault           1m21.603s
 2.  Mark Webber            Red Bull-Renault        1m21.997s   + 0.294s
 3.  Felipe Massa           Ferrari                 1m22.257s   + 0.654s
 4.  Jean-Eric Vergne       Toro Rosso-Ferrari      1m22.422s   + 0.819s
 5.  Kamui Kobayashi        Sauber-Ferrari          1m22.424s   + 0.821s
 6.  Michael Schumacher     Mercedes                1m23.404s   + 1.801s
 7.  Charles Pic            Marussia-Cosworth       1m23.982s   + 2.379s
 8.  Vitaly Petrov          Caterham-Renault        1m24.312s   + 2.709s
 9.  Gary Paffett           McLaren-Mercedes        1m24.480s   + 2.877s
10.  Bruno Senna            Williams-Renault        1m25.221s   + 3.618s
11.  Paul di Resta          Force India-Mercedes    No time

All Timing Unofficial