Novak Djokovic dug out a 6-7(4) 6-1 6-4 win over Czech Jakub Mensik on Friday to advance to the semi-finals of the Shanghai Masters, where he will face Taylor Fritz.

The four-times Shanghai champion managed to raise his level after losing the first set on a tiebreak and never looked back as he beat his 19-year-old opponent to enter the semi-finals for a ninth time.

The Serb, who played his first match on the ATP Tour over a year before his opponent was born in September 2005, initially struggled to counter Mensik's serve but found his rhythm and broke for a 5-4 lead in the first set.

However, the 24-times Grand Slam champion allowed his unseeded opponent to hit back instantly and with a foothold in the contest Mensik clinched the tiebreak as Djokovic hit a forehand into the net.

The 37-year-old did well to recover, taking advantage of a string of unforced errors from Mensik to hold serve on either side of an early break as he took a 3-0 lead in the second set.

Mensik, playing in his first ATP Masters 1000 quarter-final, had no answer to the relentless accuracy of Djokovic's forehand and was broken once again as the fourth seed levelled the match at a set apiece.

Djokovic won the first point of the decider with a pin-point forehand at the end of an epic 33-shot rally and ran Mensik ragged with his power and precision. He broke for a 3-2 lead, which ultimately proved decisive despite an apparent knee issue for the Serb late in the match.

Djokovic is looking to win a record-extending fifth title in Shanghai, as well as his first ATP Masters 1000 title since his victory in Paris last year.

He will face world number seven Fritz in the semi-finals after the American defeated Belgian David Goffin 6-3 6-4 earlier on Friday.

In the other semi-final, world number one Jannik Sinner will take on Czech Tomas Machac.