South Korea's Park Sung Hwan knocked out Lin 21-13, 21-13.
“I'm really happy because I'm moving to the next level in badminton,” Park said through a translator.
The 16th-ranked Park will next face 2004 Olympic champion Taufik Hidayat of Indonesia, who outlasted Lee 21-15, 11-21, 21-12.
“Taufik is one of the best players in the world,” Park said. “There's no such thing as a strategy for tomorrow. I will go there to learn better badminton from Taufik and maybe there will be weaknesses coming from Taufik. Then, who knows, maybe I'll be in the final.” Hidayat has won all his seven matches against Park. But that may not mean much on Saturday considering that the three-time world champion Lin had defeated Park in their last eight matches.
“I”m still not at the top of my game,” Hidayat said with a grin. “Lin Dan and Lee Chong Wei are still the top players. I'm nothing.” Hidayat was unfazed by his new status as favorite.
“I don't have pressure,” Hidayat said. “I have nothing to lose. If I win, it's OK. If I lose, it's OK too.” Standing a few feet away from Hidayat in the mixed zone, Lee again faced questions about his mental struggles.
“I think so much,” Lee said. “Each time I want to play my best for the world championships.” Lee came into the tournament as a heavy favorite after winning six titles this year.
“He (Lee) wants so much to get the title in the world championships because he never gets the big title, only the Super Series,” Hidayat said.
Meanwhile, 2009 runner-up Chen Jin of China rallied past the unseeded Hsueh Hsuan Yi of Taiwan 22-24, 21-5, 21-13, and will next play European champion Peter Gade of Denmark, who defeated Kazushi Yamada of Japan 21-19, 21-12.
In women's singles, Nehwal had become the favorite after top-ranked Wang Yihan was upset in the third round. But the second-seeded Indian lost to Wang Shixian of China 21-8, 21-14.
“Sometimes when you come and set a target in such a big tournament, it doesn't happen,” Nehwal said. “You feel bad.” Wang will face fellow Chinese Wang Xin who ousted Frenchwoman Pi Hongyan 21-13, 21-15.
Tine Baun of Denmark and Lin Wang of China also advanced to square off in the other semifinal.
European champion Baun defeated Cheng Shao-Chieh of Taiwan 21-18, 21-13, and the formerly top-ranked Lin beat Eriko Hirose of Japan 21-16, 21-17.
Baun stretched her winning streak to 17 matches.
Cheng, a bronze medallist in 2005, was limping badly after injuring her feet during a third-round match and had her socks stained with blood as she changed shoes with the score at 11-8.
Despite the injury, Cheng managed to level at 18-18 in the first. Baun then jumped to a 7-2 lead in the second set before coasting to victory.
“Sometimes she made it really hard for me,” Baun said.
“When we played rallies, she was all fit and she was running all over, she didn't give up.
“You just have to stay focused all the time. I knew we were playing for the medal at the worlds.” Baun was sidelined for four months by an injury and made her comeback at the worlds.
“I think it's amazing that after four months I can still play this game,” Baun said. “I've been feeling better all the way through each day at this tournament.” In mixed doubles, defending champions Thomas Laybourn and Kamilla Rytter Juhl of Denmark lost to He Hanbin and Yu Yang of China 21-19, 21-17, while the Chinese pairing of Zheng Bo and Ma Jin upset top-seeded Nova Widianto and Liliyana Natsir of Indonesia 21-19, 23-21.
