Stockholm - French top seed Gael Monfils struggled to hold onto a second set lead, but still battled to a 7-5, 7-5 win over South Africa's Kevin Anderson on Friday to set up a Stockholm Open semi-final against Canadian Milos Raonic.
Both players are coming back from injury, with Raonic playing his third event after July hip surgery while Monfils is back after a fortnight away with a knee problem.
The sixth-seeded Raonic unleashed 14 aces as he hammered Bulgaria's Grigor Dimitrov 7-5, 6-4 to reach his fourth semi-final of the season.
Raonic took his 2011 record to 30-16, including 11 indoor wins and just one loss.
"I took care of everything I needed to, hitting my serve and creating opportunities," said Raonic.
"The job is to take care of the serve and look for opportunities -- and I couldn't have taken care of serving any better," he said, after pounding 14 aces and hitting 34 winners in 78 minutes of power-hitting.
The second semi will pit double Stockholm champion James Blake against two-time Finnish finalist Jarkko Nieminen, who kept his title hopes alive with a 3-6, 7-5, 6-1 quarter-final victory over German Tobias Kamke.
Blake advanced without playing as the Davis Cup final hopes of David Nalbandian took a hit when the Argentine was forced to pull out before their match due to a hamstring injury.
"I felt tension in the hamstring yesterday," said Nalbandian, who is expected to play a lead role in December's Davis Cup final against Spain.
"I saw the doctor and took treatment. I tried to warm up, it was no use."
Blake, who has had his own injury worries for the last few seasons, had beaten Nalbandian in both of their previous meetings, including two months ago on hardcourt in Washington.
Monfils won the first set against fifth-seeded Anderson but had troubles closing out the second.
The Frenchman led by a set and 5-1 when his form began to slip, with Anderson battling to 5-all.
But a break for 6-5 by Monfils gave the top seed fresh life, with Monfils taking the win a game later.
Monfils remains the only player in the Top 15 without a title this season.
"I played strong but had a drop in concentration in the second set," said the 10th-ranked Frenchman, who also said he would get his wrist checked after a diving return onto the hardcourt.
"I played strong. It was a different game tonight. Kevin went for his shots, it was easier to maybe move him around the court and challenge from the baseline."
Anderson said: "I had my chances in the first and I picked it up in the second.
"I didn't have the serving day that I wanted, I wasn't hitting my spots. To get broken again at 5-5 was tough.
But I got completely back into the match. It just came down to a few points."
Raonic won his only meeting with Monfils when the 29th-ranked Canadian claimed a San Jose semi-final in February on the way to the title.
"Milos is a great server, it will be a tough match on return. He's big and tall and I need to move him as well. It's not the end of the tournament so I'm ready for the next match."
Results on the fourth day of the Stockholm Open on Friday (x denotes seeding):
Gael Monfils (FRA x1) bt Kevin Anderson (RSA x5) 7-5, 7-5
Jarkko Nieminen (FIN) bt Tobias Kamke (GER) 3-6, 7-5, 6-1
Milos Raonic (CAN x6) bt Grigor Dimitrov (BUL) 7-5, 6-4
James Blake (USA) bt David Nalbandian (ARG) - walkover (thigh injury)