HALLE: World number four Novak Djokovic booked his place in the final of Halle's ATP grasscourt tournament with an error-strewn 7-6 (9/7), 6-4 win over qualifier Olivier Rochus on Saturday. Having blasted his way past Austria's Jurgen Melzer in Friday's quarter-final, Djokovic was far from assured in the semi-final against a player ranked 136th in the world, but finally won through to his second grass final. Having raced to a 4-1 lead in the first set, Djokovic faltered badly to allow the Belgian to level and force a tie-break. It was a similar story in the second set as the Serb star seemed to be in control, only to allow Rochus to force his way back. Having earned four match points, Djokovic wasted three of them before he finally won through after nearly two hours to reach his second grasscourt final, having lost to Rafael Nadal at Queen's in London last year. He will play Germany's Tommy Haas in Sunday's final after the former world number two came out on top in a battle royal with compatriot Philipp Kohlschreiber in the other semi-final. Haas staged a remarkable fight-back after losing the first set, holding his nerve to win tie-breaks in the two final sets during a titanic struggle before claiming a 2-6, 7-6 (7/5), 7-6 (7-3) victory. 'It was a tough start for me, I wasn't happy with my racquet, the sunshine, the speed of the ball - I was thinking about other things and not concentrating enough,' admitted Haas. 'I wanted a good start and was putting myself under too much pressure. 'I was happy to force a tie-break in the second set, because I thought he had the upper hand. 'I was surprised I could turn things around, it is special for me to be in a final.' Having climbed to second in the world rankings in 2002, Haas is on his way back after a serious shoulder injury. He continues his good form after his best showing for seven years at last week's French Open in Paris, when he reached the fourth round and took eventual champion Roger Federer to five sets having held a two-set lead. Kohlschreiber, a 2008 finalist here, had been breezing his way to the final after blitzing his opponent in the first set in just over half an hour, but Haas rallied with a fine array of shots to win the second set tie-break. It looked to have been a wasted effort as Kohlschreiber raced into a 4-1, then a 5-2 lead in the third, but Haas rallied again to 5-5 and then held his nerve in the final tie-break to claim victory. It will be the 31-year-old's first final on the ATP Tour since Memphis in 2007.