LONDON: Robin Soderling's breakthrough year ended on Saturday when he couldn't protect a one-break lead.

However, the Swede's play at the ATP World Tour Finals may have convinced a few skeptics that reaching this year's French Open final wasn't a fluke.

Soderling wasted a 4-2 lead in the final set before losing 6-7 (1), 6-3, 7-6 (3) to US Open champion Juan Martin del Potro in the semifinals, sending the disappointed Swede home for the offseason after coming within reach of another big final. But he made the most of his chance to play in the season-ending tournament as an alternate, beating Rafael Nadal and Novak Djokovic in straight sets in the round-robin phase to win Group B.