Novak Djokovic gets the breaks as he targets Andy Murray's No.1 spot
Novak Djokovic became the first player through to the semi-finals at the ATP World Tour Finals in London after beating Milos Raonic. The four-time defending champion has only lost one of his last 21 matches at the O2 Arena and is guaranteed to finish top of the Ivan Lendl group after his 7-6 (8/6) 7-6 (7/5) victory.
It was not straightforward for Djokovic, who again had lapses and had to save a set point in the second set, but victory put the pressure back on Andy Murray in their world number one battle.
Djokovic said: "If I had to pick a key to the match it was just hanging in there mentally and believing the opportunities would occur. When they do, you have to capitalise, obviously. Winning the first set gave me some wings. I was twice a break up in the second set but Milos was playing well."
Raonic now faces a straight fight with Dominic Thiem, a 6-3 1-6 6-4 winner over Gael Monfils earlier, for the second semi-final place when they meet on Thursday.
The fourth seed needed to win in straight sets to book his passage through on Tuesday night, which, considering he had won just one set in seven previous meetings, was asking a lot.
At their match in Indian Wells in March, the Canadian managed only two games, but that was against the all-conquering Djokovic. The question was whether that Djokovic would show up at the O2 Arena or the distinctly less threatening version of the last few months.
The 29-year-old has appeared ill at ease on and off the court, and his victory against Thiem on Sunday was overshadowed by a terse exchange with a journalist in the press conference.
Raonic played surprisingly well against Monfils in his first match for a man who doubted he would be in London after suffering a thigh injury.
His tactic was unsubtle but also effective - serve big and do as much damage with his forehand as possible. Djokovic was on the back foot to start with and faced break points in his first two service games, but Raonic was unable to take advantage.
Djokovic settled into the match but Raonic's serving - regularly up around 140mph - kept him at arm's length.
A missed volley looked set to cost Raonic in the tie-break as Djokovic recovered from 1-3 with four straight points but HawkEye came to the Canadian's rescue when a forehand that had been called out was shown to be a winner.
Raonic then saved a set point with some huge forehands only to double fault on Djokovic's next chance.
The 25-year-old's hopes were hit further when he twice trailed by a break in the second set but Djokovic inexplicably let his opponent back in.
At 5-6, Djokovic found himself facing set point but a tense exchange ended with Raonic netting a forehand.
The tie-break again could have gone either way but Djokovic dug out a remarkable backhand half-volley at 4-5 and then took his first match point when Raonic pulled a backhand wide.
Earlier, Thiem won the battle of the debutants against an ailing Monfils to post his first victory at the tournament.
Monfils, who double-faulted three times in the final game, arrived at the O2 nursing a rib injury and said afterwards he may not play his third match against Djokovic.
Belgium's David Goffin is first alternate should the Frenchman, who is already eliminated, pull out.