Novak Djokovic overcame average form on Friday to improvise a 7-6 (8-6) 6-4 quarter-final win over Tomas Berdych at the Toronto Masters, as he beat the Czech for the 12th straight time.

The world No.1 Serb, who is bidding for a fourth Canadian title, confessed that he wasn’t at his best.

Berdych came close to lifting the hour-long first set but missed on three set points after winning five points in a row to rally from 1-3 down in the decider.

“I was very fortunate to win that first set,” Djokovic said.

“I really had some relief going into the second. I don’t know how I got out of that tiebreak.

“I guess I was just able to focus on the next point. Tomas had a double-fault (on set point) and some errors.”

Djokovic finished off his patchy victory thanks to a break in the third game of the second set as he handed Berdych a 17th consecutive loss against a top-five opponent.

The Serb stands 25-2 in their career series.

Djokovic will play for the final against the winner from Canadian fourth seed Milos Raonic and French number 10 Gael Monfils.

Second seed Stan Wawrinka broke new ground as he reached the semi-finals, producing what he called one of his top efforts of 2016.

The Swiss crushed Kevin Anderson 6-1 6-3 limiting the South African to just six aces.

Wawrinka will take on Japan’s third seed Kei Nishikori, who defeated world No. 40 Grigor Dimitrov 6-3 3-6 6-2.

Wawrinka called it “one of the best” matches of his year so far.

“It showed me that I was ready, aggressive, moving really well. I was calm, served very good and mixed up my game,” he said.

“In the past, I’ve never really played great here.

“I’m really happy to see that from the first time out on hardcourt my level is there, physically I’m feeling good, and that I can play some great tennis here.”

Wawrinka won in 73 minutes as he continues his best career showing in Canada, improving to 31-10 on the season.