London - Stan Wawrinka has warned Andy Murray not to rush his return from hip surgery after the former world number one hinted he isn't certain to compete at Wimbledon.
Murray was beaten 2-6, 7-6 (7/4), 7-5 by Australia's Nick Kyrgios in the Queen's Club first round on Tuesday in his first competitive match for 11 months.
The 31-year-old Scot, whose ranking has plummeted to 156, admitted after the defeat he was unsure if his body could hold up to the demands of best-of-five-set ties at Wimbledon.
He planned to see how he recovered before deciding whether to play at the All England Club, where he has twice won the Wimbledon title.
With Wimbledon starting on July 2, Murray doesn't have much time to regain full fitness.
And Swiss star Wawrinka, working his way back from a lengthy injury of his own, has told Murray just how difficult it is to play at a Grand Slam after so long on the sidelines.
"Well, my first match was at the Australian Open, and two days after I was not feeling pain or whatever, but my body was completely off. I felt dead," Wawrinka said.
"I lost in my next match, but I couldn't really do anything. That's mentally tough, because you have never experienced that in the past.
"So you need to learn from it, you need to adapt and accept it and be patient with yourself and what you're going to do."
Wawrinka needed two operations on a knee problem last year and, in a trend Murray will hope to buck, the three-time Grand Slam winner still isn't back to his best.
Wawrinka showed that lack of confidence and rhythm as he crashed to a 7-5, 6-7 (3/7), 6-1 defeat against Sam Querrey in the second round at Queen's on Wednesday.
"For the first match I think Andy was for sure moving, playing well, knowing that he's been away for a year," Wawrinka said.
"But if I take my experience, what's important is how he's going to be in the next match he plays.
"I know the feeling. You know, we have different injury, but for me I was also similar. I was only allowed to do certain amount of time on the court or on the physical end.
"Even when you come back on the tour, you need to still be patient, because it's not going to come back like that and you're going to be the same player as one year before."
Wawrinka faded badly in the final set against Querrey as the American world number 13 condemned the 33-year-old to his seventh defeat in his last nine ATP Tour matches.
Querrey, who won Queen's in 2010, will play Croatian top seed Marin Cilic in the last eight.
Cilic maintained his mastery over Luxembourg's Gilles Muller, hitting back to win 4-6, 6-3, 6-3 in their latest big-serving battle.
Chasing his second Queen's title and his fourth final appearance, Cilic once again frustrated Muller 12 months after beating him in the final set in both the Wimbledon quarter-finals and Queen's semi-finals.
Cilic, who lost last year's Queen's final against Feliciano Lopez, hit 19 aces to 17 from Muller as he made the quarter-finals for the seventh time.
American prodigy Frances Tiafoe moved into his first ATP Tour grass-court quarter-final with a 6-4, 2-6, 6-4 win against Argentina's Leonardo Mayer.
Tiafoe, ranked 62nd, is looking to add a second ATP title to his maiden success at Delray Beach in February.
The 20-year-old out-lasted Mayer to stop the world number 38 building on his surprise first round victory against third seed Kevin Anderson.
Tiafoe next faces France's Jeremy Chardy, who beat Russia's Daniil Medvedev 7-6 (8/6), 6-3.
Results at the ATP Queen's tournament in London on Wednesday (x indicates seed):
Marin Cilic (CRO x1) bt Gilles Muller (LUX) 4-6, 6-3, 6-3
Sam Querrey (USA x5) bt Stan Wawrinka (SUI) 7-5, 6-7 (3/7), 6-1
Jeremy Chardy (FRA) bt Daniil Medvedev (RUS) 7-6 (8/6), 6-3
Frances Tiafoe (USA) bt Leonardo Mayer (ARG) 6-4, 2-6, 6-4