Defending champion Novak Djokovic and tenacious Spanish fourth seed David Ferrer spent nearly eight combined hours on court on Thursday, as both earned marathon wins to set up a semifinal at the US Open.

Second seed Djokovic went past the three-hour mark in his gripping 6-2, 7-6 (7-3), 6-4 quarterfinal win over 2009 champion Juan del Potro.

Ferrer fought for four-and-a-half hours for a place in his second career semifinal at Flushing Meadows, as he wore down Janko Tipsarevic 6-3, 6-7 (5-7), 2-6, 6-3, 7-6 (7-4).

The other men’s semifinal line-up was decided on Wednesday, when Andy Murray came back against Marin Cilic and Tomas Berdych stunned five-time champion Roger Federer.

Djokovic went through in three sets over Del Potro, but the Serb admitted that it seemed like a lot longer, especially considering the 17-minute game, in which del Potro saved three set points to force a second set tiebreaker.

“I remained positive and trying to get back into the game,” said Djokovic. “I had a couple of set points but he came up with big serves and his big forehand.

Djokovic summoned his reserves to win the decider for a two-sets-to-love lead but then had to fight just as hard to put away the third set.

“I was lucky to get out of the second set with the lead. We played some incredible points. I’m really happy to be in the semis.”

“It will be another big battle,” he said of the Saturday confrontation with the Spaniard. “He is one of the most consistent players in recent years. He’s been in the top five and I have a lot of respect for him.”

“Maybe I can compare with Davis Cup,” said Ferrer. “It was a very emotional match, one of the best emotional matches of my career.” Tipsarevic, who has never been to the final four of a major, looked dead on his feet in the final set after his exertions.

He gripped at his right groin in some pain midway through the ninth game of the last set, stopping after going down two break points to get taped up at his chair. He then came back out and won four consecutive points to hold for 4-5 before finally going down to a man he last played four years ago in the Beijing Olympics.

“I’m feeling pain on my left hip now,” the Serb said later. “I don’t feel the muscle right now walking. I’m going to do a treatment with my physio afterwards and see what is going on. My legs are definitely feeling pain right now.”

Keywords: 2012 US Open

More In: Tennis | Sport