Shanghai: Top-ranked Novak Djokovic dropped a hint that he may split with coach Boris Becker on Thursday after progressing to the quarter-finals of the Shanghai Masters.
Djokovic, who says he is taking a fresh mental approach after struggling in recent months, revealed that he had made no plans about retaining Becker in his team next year.
"We are still working (together), yeah... for now the plan is the rest of the season, what's left, indoor tournaments," said Djokovic.
Asked what would happen next year, the defending champion said: "We still haven't talked about it."
Becker joined Djokovic's coaching team at the start of 2014, helping him win six of his 12 Grand Slam titles and put together one of the all-time great seasons last year.
Speculation about their partnership has grown since the Serb suffered a crisis of motivation and a series of injuries since completing a career Grand Slam at the French Open.
Djokovic lost in Wimbledon's third round and in round one at the Olympics before reaching the US Open final, while also enduring wrist and elbow problems and admitting "private issues".
"I don't think about any trophies or number ones in the world, rankings, anything like that. It's completely different," he said this week, explaining his new approach.
Djokovic skipped last week's China Open with his wrist injury but he was in impeccable form as he dismantled Canadian qualifier Vasek Pospisil 6-4, 6-4 on Thursday.
Second-ranked Andy Murray, who is gunning for Djokovic's world number one crown, was even more impressive as he walloped Lucas Pouille 6-1, 6-3.
Murray didn't face any break points against France's Pouille as, like Djokovic, he raced into the last eight without dropping a set.
In further action on Thursday, America's Jack Sock beat Milos Raonic 0-6, 6-4, 7-6 (10/8), ending a run of eight straight defeats to the Canadian fifth seed.
And Jo-Wilfried Tsonga ousted racquet-smashing teenager Alexander Zverev, denying the young German a potential match-up with his older brother, Mischa.
Zverev, 19, pushed the ninth seed all the way until he was broken for 5-6 in the third set, prompting a furious racquet-battering which earned him a warning for unsportsmanlike conduct.
Tsonga, serving for the match, safely negotiated three break points before a spectacular airborne smash set up match point, which he gobbled up to win 6-7 (4/7), 6-2, 7-5.
Zverev's brother Mischa, a decade older at 29, also went three sets against Marcel Granollers of Spain but he won 6-7 (4/7), 6-4, 6-1 to set up a meeting with Djokovic.
The Zverevs were the first brothers since Olivier and Christophe Rochus at Miami 2006 to reach the last 16 of a Masters tournament, and were on course to meet in the semis.