Summary Djokovic found himself down a set and a break against the Gulbis whose form comes and goes.
MONTREAL (AFP) - Novak Djokovic had to fight off an upset bid from qualifier Ernests Gulbis, defeating the Latvian 5-7, 7-6 (9/7), 6-1 on Friday to reach the semi-finals of the Montreal Masters.
But Rafael Nadal, like Djokovic a former champion at the event, was unable to escape an on-form Kei Nishikori as the fourth seed sent out the Spaniard 6-2, 6-4 thanks in part to six double-faults from Nadal.
The red-hot Nishikori is riding a wave of momentum from his hardcourt title last week in Washington and will next face second seed Andy Murray who beat French 10th-seeded holder Jo-Wilfried Tsonga 6-4, 6-4 and took revenge for a semi-final loss a year ago in Canada.
Nishikori won his first match against Nadal after seven losses, taking just under 90 minutes to advance in his best Canadian showing.
"It took a long time to finally beat him, but I m very happy to win my first match against Rafael," said Nishikori.
"I knew I have to be aggressive, so I have to change some tactics to play against Rafa.
"Everything was feeling well today. I felt like everything was going in.
"I mean, he s still not maybe 100 per cent, but he s Rafa."
Seventh seed Nadal was playing in Canada for the first time since winning his third title here in 2013 and he now stands 28-7 in the country.
Djokovic found himself down a set and a break against Gulbis.
Gulbis, whose career best was a Roland Garros semi-final in 2014, has since gone into a funk in 2015.
But he forced his world number one to save two match points in the second-set tiebreaker of a thriller lasting two and a half hours.
Djokovic levelled at a set apiece and re-established order as he ran away with the third set for the win.
"Ernests was a better player for two sets -- unfortunately he missed two match points," Djkovic said.
Muscle it out
"I wasn t very happy with my game. But you have to muscle it out sometimes and I had to put in the effort.
"One day you play well, the other you don t. It s important to stay committed to every point, believe, fight. That s what gets you out of trouble."
Djokovic is bidding for his fourth Canadian title and the win puts him into a semi-final against unseeded Jeremy Chardy.
Chardy booked his first career appearance in the semi-final of an ATP Masters 1000 event, struggling for three hours to defeat John Isner 6-7 (9/11), 7-6 (15/13), 7-6 (7/4).
Chardy overcame 32 aces from the big American to reach the final four.
The match, which began two hours late due to rain, lasted three hours and eight minutes.
"I m very proud to reach my first Masters semi-final," said the 49th-ranked winner who levelled his season record at 18-18. "I was lucky to come back in the second.
"I m really happy. I stayed really focused and really strong in my head the whole match."
Chardy advanced with 12 aces and a single break of serve while saving break points on six of seven occasions.
The Frenchman has cast a spell over Isner in their career meetings, winning all four of their matches including at Roland Garros in the second round in May.
