Fernando Alonso has clocked the fastest time on the first day of in-season testing at Mugello.
The Spaniard recorded a best time of one minute and 22.444 seconds on a rain-affected day.
Mark Webber was second, 1.204 seconds behind Alonso while Jean-Eric Vergne was 1.447 seconds back in third place.
With rain returning during the afternoon, times recorded in the morning after the track had initially dried proved to be the day's fastest.
Better weather is forecast when further testing takes place on Wednesday and Thursday, when world champion Sebastian Vettel is scheduled to drive.
The test features 11 of the 12 F1 teams, with struggling HRT having dropped out to concentrate on the relocation of their factory to Madrid.
Ferrari are hoping the session will help reignite what has been a disappointing season.
Alonso has not qualified any higher than ninth in the four races so far, although he did claim an unexpected victory in the Malaysian Grand Prix.
The 30-year-old will be keen to move up the drivers' championship when racing resumes at the Spanish Grand Prix on 13-15 May.