Former champion Marcos Baghdatis rediscovered some of his best form at the Sydney International on Thursday, ousting top seed Juan Martin del Potro from the quarter-finals in two close sets. The Cypriot world number 43 knocked the last seed out of the tournament with a 7-6 (9/7) 6-4 victory in one hour and 40 minutes. Baghdatis, who won the Sydney title two years ago, will face Frenchman Julien Benneteau in Friday\'s semi-finals after Benneteau beat Russia\'s Alex Bogomolov Jnr 6-2, 6-4. \"I played great today, I had a not so good match yesterday in tough conditions and (my coach) just said to go for it and I went for it,\" Baghdatis said after beating the former US Open champion. \"I was playing really aggressive. It was great.\" Del Potro had looked in control in the first set, having broken Baghdatis in the seventh game, but Baghdatis broke back to 5-5, before both players held serve to force a tie-break. Del Potro took the early advantage and had two set points but Baghdatis saved both and then needed one set point of his own to take out the set. Baghdatis made the decisive break in the seventh game of the second set, before serving out the match. \"Marcos played really well in the important moments, and I had a chance in the first set and I didn\'t take it,\" the Argentine said. \"When you lose every chance and the opponent is like Marcos, you will lose. \"Marcos played better and better during the match. At the end of the match he was completely confident with his game and make a lot of winners with the backhand and forehand and was really tough.\" Uzbekistan\'s Denis Istomin and Jarkko Nieminen of Finland will fight out the other semi-final. Istomin proved too strong for French third seed Richard Gasquet 6-4, 7-6 (7/4), while Nieminen eliminated American Bobby Reynolds 6-3, 6-3.