Stefanos Tsitsipas fired off sharp criticism of his father-coach on Thursday after suffering a 6-4, 6-4 second-round loss to Japan’s Kei Nishikori at the ATP Montreal Masters.

The Greek star, who has slipped out of the ATP top 10 in recent months to now stand 11th, has won just two titles in two seasons — in Mexico last year and this year at the Monte Carlo Masters.

After going down to the 34-year-old Nishikori, the two-time Grand Slam finalist let out his career frustrations.

“Masters 1000 matches are important, I need a coach who listens to me as a player,” he said.

“My father has not been very smart in handling some situations, in trying to read what is happening on the court.”

Should Tsitsipas ditch his father Apostolos, his mentor since childhood, it would not be the first family feud between the pair.

In late 2022, Tsitsipas took Greek-Australian former US Open finalist Mark Philippoussis onto his team. The pact lasted until May 2023, when the Aussie departed and Apostolos returned to the fold.

The elder Tsitsipas has a reputation for badgering his son between nearly every point and was called out for then-illegal coaching from the player box before the practice was recently permitted.

“It has been a poor performance from my father and it’s not the first time,” Tsitsipas said of his parent. “I’m disappointed with him.

“The most important thing is to have good direct feedback, the coach needs to listen. The player is the one holding the racquet.

“I have power here to some degree but it should be a collaborative effort on both sides, for me to develop my tennis.”