Novak Djokovic defeated his good friend Vasek Pospisil to reach the semi-finals of the Tel Aviv Watergen Open.

Having eased past Pablo Andujar on Thursday in his first ATP Tour match for more than four months, Djokovic had a tougher time of things against Canadian Pospisil before sealing a 7-6 (5) 6-3 triumph.

The pair teamed up to found the Professional Tennis Players Association three years ago, and 149th-ranked Pospisil did not face a break point in the opening set.

He then fought back from 5-1 down in the tie-break with four points in a row before Djokovic took it, while in the second set the Serbian won the final three games after seeing an early break slip away.

“It was a great, positive win,” Djokovic said in his on-court interview. “Vasek is one of my best friends on the tour.

“We have known each other for many years. It is never easy playing someone you respect so much and like so much, but we are both professionals and wanted to win the match and you can see that.

“I think the level of tennis was really high. Especially towards the end of the first set and the second set. Credit to him for fighting. Great to see him back.”

In the last four, Djokovic will take on Russian Roman Safiullin, while the other semi-final pits second seed Marin Cilic against France’s Constant Lestienne.

There was a major shock at the Korea Open, where Japan’s Yoshihito Nishioka knocked out top seed Casper Ruud 6-2 3-6 6-2.

The US Open finalist’s defeat means Rafael Nadal will overtake him as world number two next week.

Second seed Cameron Norrie withdrew ahead of his quarter-final against Jenson Brooksby through illness. The American will take on Denis Shapovalov in the last four, while Nishioka meets lucky loser Aleksandar Kovacevic, who is having the best week of his career.