Novak Djokovic came through his toughest test at Wimbledon so far, beating the hard-hitting Tomas Berdych in straight sets to make his 13th consecutive grand slam semi-final.
Djokovic wasted four break points in the first set and was broken twice in the second, but he ultimately came through to record a deserved 7-6 (7/5) 6-4 6-3 win against the seventh seed.
The top seed, who is yet to drop a set in the tournament, will play Juan Martin Del Potro in the last four and is still on course to play Andy Murray in the final.
Djokovic admitted afterwards that he thought he could have lost the match.
The 2011 champion told the BBC: "It was a strong start for me today.
"I had a few break points, a few chances to break in the first set, but I didn't manage to do that and the tie break was decided by one mistake with a forehand at 6-5.
"It was a very close match, it could have gone either way. He could have won the first two sets, he had a double break in the second.
"I don't know how I managed to go ahead, I don't know how I turned it around. I am really happy with the performance. I am playing some of the best tennis on grass of my career."
Djokovic was glad to see fellow Serb and Manchester United captain Nemanja Vidic in the crowd, along with former Chelsea striker Andriy Shevchenko, who had also come to watch.
"It really means a lot to see Nemanja with Andriy here," Djokovic said.
"I have only met (Vidic) once before briefly, but we are glad that he accepted the invitation to come."
Vidic, who snubbed a ticket in the Royal Box on Centre Court to come and watch his compatriot, saw Djokovic fly out of the blocks.
The world number one fired down two big returns to earn a pair of break points, but Berdych saw off the challenge with a couple of forehand winners.
Djokovic is used to overpowering his opponents from the back of the court, but today he met his match in the big-hitting Berdych in the first set.
The Serb often had to station himself six feet behind the base line in order to deal with Berdych's big returns, which sent his opponent slipping and sliding across the court.
Djokovic spurned another break point in the seventh game when he returned long and he vented his frustration by yelling and striking the net with his racquet.
Berdych saved another break point with a 129mph ace. Both players broke each other twice in the tie-break, but Djokovic struck the killer blow on his only set point, forcing his opponent to go wide following a powerful return.
Winning the first set had a bad effect on Djokovic's nerves as he was surprisingly broken twice to go 3-0 down in the second set.
The Serb soon woke up, though, breaking Berdych twice in quick succession to level the set at 3-3.
The crowd shrieked with joy and excitement as the two players engaged in a thrilling rally, but a tense atmosphere then descended on Court One as Berdych took serve attempting to stay in the set at 5-4 down.
The seventh seed fired a forehand wide to give the world number one two set points and he took the second when Berdych wastefully hammered the ball into the net following a weak return from the favourite.
Berdych took little time to crumble in the third set, double-faulting in the third game to offer Djokovic a break point. Djokovic had nothing to do to go ahead as Berdych double-faulted again and the former champion moved 3-1 up.
The Serb was now in full flow, pulling his best shots out of the locker, and victory seemed inevitable.
Djokovic earned three match points in the ninth game and he achieved victory when his opponent put a return into the net, bringing Vidic and the rest of the Court One crowd to their feet.