Paris - Novak Djokovic extended his win streak to 20 at the Paris Masters on Friday, defeating Tomas Berdych 7-6 (7/3), 7-6 (10/8) to reach the semi-finals.
Andy Murray and David Ferrer also made it through to the last four in the bottom half of the draw on a day of marathon clashes, but Rafael Nadal crashed out to Stan Wawrinka.
The straight sets victory for world number one Djokovic also meant that he has now won 28 sets in a row - the best run of his career - dating back to the US Open final in early September.
But he had a battle on his hands against fifth-seeded Berdych, a winner in Paris 10 years ago when he was just 20.
Neither player could manage a break of serve, the first time that has happened to Djokovic in 680 career wins, according to ATP statistics.
"It was decided in tiebreaks two times, and very few points, really, decided a winner today, Djokovic said.
"Could have gone a different way. He had set point in the first set, as well. In the important moments, I just managed to hang in there, you know, just stay tough. That's what I'm most proud of."
Despite having lost all 16 of their previous hardcourt matchups, the towering Czech had the better of the first set behind a powerful display of serving and forehand blockbusters.
Berdych kept his nose in front and his chance came with a set point at 6-5 up only for Djokovic, the top seed and defending champion, to produce a big first serve and a forehand winner off the blocked return.
The tie-break, however, was dominated by the Serb winning four of the first five points to take control.
Serves again dominated in the second set with both men holding firm to bring up a second straight tie-break which Djokovic edged 10/8 despite Berdych having another set point.
Djokovic will next play Wawrinka, who sent Nadal packing 7-6 (10/8), 7-6 (9/7), the Swiss having defeated him the last time the two men met in Paris in the French Open final in June.
That defeat prevented Djokovic from accomplishing the fabled calendar year Grand Slam which only two men - Rod Laver and Don Budge - have ever achieved before. He won the Australian and US Opens as well as Wimbledon.
The other semi will oppose second seed Murray against 2012 champion Ferrer.
Murray made the last four of the Paris indoors for the first time, but it needed a marathon effort to see off the last remaining Frenchman, Richard Gasquet.
The second seed, who had dropped just four games in reaching the last eight, was kept hard at it for two hours 38 minutes before edging through 7-6 (9/7), 3-6, 6-3.
Five times previously Murray had fallen in the quarter-finals of the ATP's regular season finale.
"I think the level during the first set was extremely good," Murray said.
"After that it was a little bit up and down. But I just managed to hang in at the end after losing the momentum really in the second set."
The win meant that Murray joined Roger Federer, Nadal and Djokovic as the only players to reach the semi-finals or better at all nine of the Masters 1000 Series tournaments during their career.
Ferrer, who won the 2012 tournament in Paris, looked set for a straight sets canter against John Isner as he led 6-3, 5-3, 40-15.
But the big-serving American, who defeated Federer in the previous round, suddenly found some form with his returns to break back and then draw level at 5-5.
Isner jumped out into a 5-2 lead in the tie-break before Ferrer pulled back, but it was the American who levelled the set scores against all the odds.
The effort though took its toll on Isner who dropped serve early on in the decider and then needed lengthy courtside treatment for stomach pain.
Ferrer had his second chance to put away the tie and this time he made no mistake winning 6-3, 6-7 (6/8), 6-2.
Results on the sixth day of the ATP Paris Masters on Friday (x denotes seeded player):
Novak Djokovic (SRB x1) bt Tomas Berdych (CZE x5) 7-6 (7/3), 7-6 (10/8)
David Ferrer (ESP x8) bt John Isner (USA x13) 6-3, 6-7 (6/8), 6-2
Andy Murray (GBR x2) bt Richard Gasquet (FRA x10) 7-6 (9/7), 3-6, 6-3
Stan Wawrinka (SUI x 4) bt Rafael Nadal (ESP x7) 7-6 (10/8), 7-6 (9/7)