Haas Rallies for Third Time to Overcome Nieminen
Haas has battled a shoulder injury all week but the German once again overcame a poor first set to dispatch the 11th-seed in the first evening quarterfinal match.
Nieminen was playing his second match of the day after having to complete his third round match Friday morning.
Despite the third consecutive comeback win, Haas is concerned his ailing arm may not hold out for the weekend.
"Sometimes it's worse than others and sometimes it goes away after a few points and I feel nothing," Haas said.
"I'm wondering what s causing the problem -- I've been talking to so many doctors. "But I'm still enjoying myself out there and playing good tennis. If the arm feels like this tomorrow there is no way I can play."
In other quarterfinal action, fifth-seeded Alex Corretja of Spain advanced to the last four when Paul-Henri Mathieu of France retired trailing 2-5 in the first set with blisters on his left foot.
"You never like winning this way but if I have to be honest it came at a good time for me after two tough matches," Corretja said. "I'll get some rest and get ready for tomorrow."
Number seven seed Juan Ignacio Chela of Argentina defeated Mardy Fish 7-5 6-3 to also advance.
Chela trailed 1-3 in the second set but won five consecutive games to close out the match.
"I'm really happy to be in the semifinals and it would be great to win my first hard court title," Chela said. "I'm very happy with my game, my confidence is high and I would prefer to go into the U.S. Open next week having played a lot of matches."
In the final night match, Thailand's Paradorn Srichaphan upset fourth-seeded Younes el Aynaoui of Morocco 5-7 6-3 6-4 to continue a fun of form that has given him nine victories in his last 10 matches, Reuters reported.
Earlier in the day, Nieminen advanced to the quarterfinals when he defeated Brazilian Flavio Saretta 2-6, 6-3, 6-4.
The match was postponed because of rain Thursday night with Saretta leading 3-1 and was completed on Friday morning.