Highcroft has confirmed that Dario Franchitti will rejoin David Brabham and Scott Sharp in its driver line-up for the Petit Le Mans later this month.
IndyCar Series star Franchitti had previously driven for the squad in the Sebring 12 Hours, and was also recruited for last year's Petit Le Mans, although the car crashed out before he could race it.
The Road Atlanta event on 26 September is set to be the most hotly-contested event of a difficult season for the American Le Mans Series. At most races the Highcroft and De Ferran Acuras have been the only competitive LMP1 cars in the field, but Audi and Peugeot are returning for Petit, and ORECA is also coming across from Europe for the event.
"It is certainly an exceptional field with Audi, Peugeot and also the ORECA guys coming over," said Franchitti. "The P2 cars are also very impressive and been quite close to the P1 cars from time to time. Obviously I have been keeping an eye on my brother Marino and the Dyson boys as well."
Brabham and Sharp are currently 17 points ahead of De Ferran's Gil de Ferran and Simon Pagenaud in the ALMS LMP1 championship, and Franchitti is keen to help Highcroft secure the crown.
"My job at Petit is certainly to be a team player - I'm not out there to be a star - I have to be conservative and make sure I hand the car back in perfect condition at the end of my stints," he said.
"Pulling off a strong finish will be extremely important for Patron Highcroft Racing's championship aspirations."
Franchitti, who is also in contention for the IndyCar crown with two rounds to go, believes he will be able to contribute more to Highcroft now he has had a full season back in the IndyCar Series, having spent 2008 in NASCAR.
"Before I tested the LMP2 car prior to Petit last year, the previous run I had done on a road course was in a Nationwide Series car which was 20 seconds a lap slower around Road Atlanta," he said.
"When I got back in the Acura I was still getting up to speed with the performance of the prototypes initially.
"With driving IndyCars for the whole season the performance is a lot more similar to the sportscar so that should help me get up to speed a lot quicker in the limited amount of track time we have available."
De Ferran has already announced that Franchitti's Ganassi IndyCar team-mate - and title rival - Scott Dixon will be drafted back into its squad for Petit. Dixon claimed pole for the team at Sebring at the start of the year.