World number two Rafael Nadal recovered from a slow start to keep his Masters Cup hopes alive with a 7-6 6-2 win over his fellow Spaniard Tommy Robredo on Wednesday.

His victory meant that James Blake became the first player into the semi-finals after the American fought back to beat Nikolay Davydenko 2-6 6-4 7-5 in the earlier Gold Group match.

Rafael Nadal of Spain hits back to Tommy Robredo of Spain during their match at the Masters Cup tennis tournament in Shanghai, China November 15, 2006.[Reuters]

Nadal will play Davydenko on Friday for a place in the last four, while Robredo, who had already lost to the world number three, cannot now qualify for the knockout stage.

"I'm very happy with my victory because it was difficult to lose the first match," said Nadal, who lost to Blake in his opener. "It was very important for me. If I lost, I was out of tournament."

Nadal initially continued where he left off against Blake on Monday and sixth-ranked Robredo took advantage of his lacklustre start to break the French Open champion for a 4-2 lead.

That seemed to galvanise Nadal and he broke straight back but Robredo, who had lost all three of their three previous meetings, stuck doggedly to his task to force a tiebreak.

James Blake of the U.S. reacts during his match with Nikolay Davydenko of Russia at the Masters Cup tennis tournament in Shanghai November 15, 2006.[Reuters]

Nadal raced out to a 5-1 lead with his best tennis of the day and found a superb down-the-line winner to claim the first set in just over an hour.

Another break early in the second set put Nadal on course for victory. Although Robredo had three chances to break back, Nadal saved them all to win his first Masters Cup match when his opponent went long.

"I feel good," Nadal said. "I was playing good with my forehand, with my backhand okay, too, and serving with confidence. So I played a complete match. I am very happy."

Robredo thought he had played well but it just had not been good enough.

"I had my chances in the first set," he said. "Well, that's it. That happens when you play with the world number two. If you have your small chance and you don't take it, then maybe you're going to lose."

MENTAL RESILIENCE

American Blake lost his first five service games before rediscovering the mental resilience that got him past Nadal as he came back from a set and a break down against Davydenko.

The 25-year-old New Yorker, playing in his first Masters Cup, first got his serve in order in the second set before ramping up the power in a match of two halves against the tiring Russian.

"Once I started ... getting the momentum, I felt good," said the world number eight.

"Obviously, he still could have won. A point here or there, he easily could have won that third set. I just felt like the momentum was in my favour, I was playing great."

Blake teed himself up for a fifth victory in five attempts against the Russian by lashing a beautiful return into the corner and won the match when Davydenko went wide on the next point.

Davydenko, aiming to reach the semi-finals for a second successive year, said he had not prepared well enough to take on the players from the top eight in the world over three sets.

"I was just losing power because I was losing concentration because I was ... very tired," said the 25-year-old, who blamed illness not his 31 previous tournaments this year for his fatigue.