MARSEILLE - Juan Martin Del Potro of Argentina beat top-seeded Jo-Wilfried Tsonga of France 6-4 6-7 6-3 in an Open 13 semifinal yesterday. Del Potro will face 2010 champ Michael Llodra in the final after the Frenchman upset third-seeded Janko Tipsarevic of Serbia 6-4 7-6.

Tsonga outslugged Del Potro with 26 aces to 15, but made too many unforced errors against the 2009 U.S. Open champion, who has reached his second final in two weeks.

Del Potro broke for a 2-0 lead in the final set when Tsonga netted a backhand volley. He clinched victory on a backhand from Tsonga that sailed wide.

Both players struggled to hit their stride.

Tsonga made a double-fault and three unforced errors to drop the opening game. He broke back in the fourth game but then made a forehand error to give Del Potro a 3-2 lead.

Del Potro slammed an ace to save a break point at 3-2 and whipped a forehand winner to erase another one at 4-3, before taking the first set with a service winner clocked at 208 kph (129 mph ).

Tsonga, who won this tournament in 2009, raised his game in the second set by hitting 26 winners to Del Potro's 16.

Del Potro saved a set point at 5-4 to force a tiebreaker. It was then Tsonga's turn to hold his nerve by saving a match point at 8-7. Tsonga hit a forehand volley to convert his fifth set point and level the match.

Del Potro lost to Roger Federer in the ABN Amro final last Sunday in Rotterdam, Netherlands.

In the second semifinal, Tipsarevic sent an approach shot into the net to drop serve at 5-4 and lose the opening set.

Llodra saved six set points in the tiebreaker and converted his first match point when Tipsarevic hit a forehand wide.