The Patr?n Highcroft Racing team kicked off its assault on the 2009 Mobil 1 Twelve Hours of Sebring with all three of its drivers getting the chance to sample the new Acura ARX-02a, but also the first technical hiccup of the week.

Scott Sharp began the day in the #9, but his efforts were curtailed by a gearbox issue which sent the car back to the paddock earlier than anticipated. The afternoon session ran without problems, however, with both David Brabham and Dario Franchitti getting valuable time behind the wheel.

''These first couple of days are all about giving each driver some seat time and getting as much running done as we can before the weekend,'' Sharp explained, ''I had a good practice session this morning and worked through quite a few items on our checklist, but I had a bit of a gearbox issue which ended our session a little early.

''We all realise this is a young programme. We've covered a lot of ground already, but we have a long way to go and it is a challenge to tackle the first race of the year against the two toughest competitors in the sports car world in Audi and Peugeot. However, everyone has been working non-stop and, provided we can stay out of trouble and stay in contention all day, we can end up with a good result.''

Brabham took over at the start of the afternoon session, undertaking a number of tyre evaluation runs before handing over to Franchitti, who joins the line-up for Sebring before embarking on his run to the IndyCar Series.

''After all the testing we have done, it is great to get to Sebring and kick off race week - this is where it all counts,'' Brabham noted, ''We have been making some pretty good progress today, with some changes and tyre evaluations with Michelin, but we still have quite a few changes to make overnight and we will see what tomorrow brings.

''It is a step-by-step process for us, but the car is getting more and more reliable and we only had one small issue this morning. Having a trouble-free run is the key thing we need to focus on.''

The Patr?n machine finished the day sixth fastest, stopping the clocks at 1min 45.871secs, already nearly two seconds a lap faster than the team's LMP2 qualifying time from Sebring in 2008 but with the promise that there would be more to come.

''We tried a few things on the car - some of which worked, some of which didn't,'' Franchitti revealed after getting a handful of laps in the ARX-02a at the end of the day, '' The overall balance was off quite a bit this afternoon. We had a reasonable car at the endurance test, but we are now trying to improve on that and trying different things.

''The track will start to grip up quite a bit as the week goes on, but it is almost a trade-off because it can get slower as it gets hotter. Sebring is well known for that and it is almost like an oval in some ways - the grip level can just die off when it gets hot. It certainly makes it challenging in a twelve-hour race because you experience so many different temperature conditions.''

Testing continues with two sessions today [Tuesday], before official practice for the 12 Hours begins on Wednesday.