Andy Murray said Sunday it was going to be "difficult" for the former world number one to reach his level of old after a lopsided defeat by fellow three-time Grand Slam champion Stan Wawrinka in the French Open first round.
Murray suffered his joint-worst defeat at a major in terms of games won, succumbing to 2015 Roland Garros winner Wawrinka 6-1, 6-3, 6-2 in the opening day's marquee match.
"I need to have a long, hard think about it. It's not for me the sort of match I would just brush aside and not give any thought to," Murray told reporters.
"I should be analysing that hard and trying to understand why the performance was like that."
Murray, who needed a wild card to play in Paris this year, was competing in a clay court tournament for the first time since his five-set loss to Wawrinka in their 2017 French Open semi-final.
The Scotsman, who cited that match as "the end of my hip", has been running a long battle ever since with an injury that at one stage threatened to destroy his career.
"It's going to be difficult for me to play the same level as I did before," said Murray.
"I'm 33 now and I was ranked No. 1 in the world, so it's difficult with all the issues that I have had.
"But I'll keep going. Let's see what the next few months holds, and I reckon I won't play a match like that between now and the end of the year."
Wawrinka fired 42 winners past a subdued Murray, who made barely a third of his first serves and was broken six times.
"From a physical perspective I wouldn't expect to physically be the same as what I was before I had the operation," Murray added.
"But in terms of like ball striking and in terms of my strokes and stuff...there is no reason that I shouldn't be able to do that from a technical perspective."