Veteran Simon took advantage of an off-colour Thiem to secure the opening set, and he led by a break early in the second.

But Thiem, fancied by many as one of the few players to challenge Rafael Nadal's dominance at Roland Garros, found a new gear to record a 3-6 7-6 (7-1) 6-1 victory and win a second trophy on clay this season.

The Austrian consequently wins a 10th ATP Tour title, extending his winning streak over Simon to six matches in the process, and he will now switch focus to his first-round tie with Ilya Ivashka at Roland Garros.

Simon had already seen two break-point chances go amiss in game four before a wide backhand from Thiem gifted the Frenchman a 4-2 first-set lead he would not relinquish.

Thiem appeared sluggish, perhaps a result of having to finish his quarter-final win over Guillermo Garcia-Lopez before beating Dusan Lajovic in the semi-finals, and a double fault followed by a wild forehand saw Simon break immediately in the second set.

But the tide began to turn and, after holding in a mammoth game six, Simon could not repeat the trick when Thiem broke back in another lengthy game to level the set at 4-4.

Thiem went on to dominate the breaker, winning seven straight points after losing the first, and with the momentum on his side broke twice en route to racing into a 4-0 lead in the decider.

Simon avoided the final-set bagel, but the writing was on the wall and Thiem put the match to bed with a fierce forehand on his second match point.