Top seed Rafa Nadal moved into the semi-finals of the Shanghai Masters on Friday when Ivan Ljubicic became the eighth player to retire from the $3.24 million tournament.
The Spanish world number two had just evened the match up at 3-6, 6-3 when 30-year-old Ljubicic, who had already had treatment on his left thigh, decided he could no longer continue.
Nadal, who lost to another big-serving Croatian in Marin Cilic at the China Open last week, will face compatriot Feliciano Lopez on Saturday hoping to reach his first final since knee and abdominal injuries disrupted his season.
Second seed Novak Djokovic earlier came through a tough test of his nerve at the hands of Gilles Simon to set up a semi-final against sixth seed Nikolay Davydenko with a 6-3, 2-6, 6-2 victory.
The 22-year-old, chasing a third successive title in China after last year's Masters Cup triumph and last week's victory in Beijing, needed to show real mental strength in a frenetic third set against the French hustler.
The pair traded two breaks each in a dramatic first four games, Djokovic at one stage going from chest-pounding delight to racket-smashing fury in a matter of three points.
"Most of the time when I smash the racket the things go better from then on," said Djokovic. "The positive thing is that I managed to find a good solution after so many ups and downs from both sides. A very emotional, very intense match."
The Serbian, who will be world number three again next week, broke Simon again for 3-2, and was the first to hold serve before rattling through the remainder of the set.
Sixth seed Davydenko earlier survived a tactical switch which won Czech Radek Stepanek the second set to claim a 6-1, 4-6, 6-1 victory.
Davydenko stood firm through pressure on his serve early in the deciding set before re-establishing control and racing to a comfortable victory.
Djokovic crushed Davydenko in the 2008 Masters Cup final at the Qizhong arena.
"I had no chance," Davydenko said. "He played very good baseline. Really, I could not do anything. If I still have good control, maybe I have a chance."
Spain's Feliciano Lopez upset ninth seed Robin Soderling 7-6, 6-3 to reach his first semi-final of the season.
The world number 41 needed a tiebreak to win the first set against the big-serving Swede but broke early in the second and never looked back, clinching victory in 94 minutes.
Lopez dropped his racket and raised his eyes to the evening sky in celebration after his biggest win of the year.
"I just tried to play my best tennis and to play my best weapons as best as I can," he said. "It's my first semis, and I'm so happy."
