Andy Murray slams his own ‘unacceptable’ display and fitness in Gilles Simon defeat at Paris Masters in Bercy

The three-time Grand Slam winner slipped from a set and a break up to a 4-6 7-5 6-3 defeat to 37-year-old Simon, who is calling time on his career at the end of this tournament.

Murray had been in pole position to advance at 5-3 up in the second set, but the 35-year-old was then left licking his wounds going into the off-season.

“There’s no guarantee that I win that match, but when you lose matches, and it feels like it’s down to your physicality, it’s really, really disappointing.

“It’s nothing to do with my hip. I think just the reality is I need to work harder. Obviously, there’s certain things I can and can’t do nowadays, I need to be a bit more careful with some of the training that I do.

“But I can certainly do more than what I have done and push myself harder than what I have done recently. What I’m trying to do is extremely hard. I need to do exceptional things to still compete.”

Murray, who started working with coach Ivan Lendl again earlier this year, suggested he may have got his summer schedule wrong after Wimbledon, admitting gym time could have been more favourable than minor tournaments before the US Open.

“If I’m being completely honest, I don’t think the last four or five months that that’s necessarily been happening, since the issue sort of started in Newport, Washington time,” he added.

“Usually I would dedicate more time to my training and more time, you know, like training blocks in hot climates and things like that. So it’s something that I’ll have to look at.

“Maybe one of the mistakes that I made was like playing Newport (after Wimbledon). I could have done a training block there to get in the heat and prepare better for the summer.

“I’ve not really done much since the US Open, like, physically in the gym, or anything, very, very little.

“I’m probably conditioned in some ways for tennis, because my body is responding well to the matches. I know I’ll wake up tomorrow, and I’ll feel okay. But from an endurance perspective, that’s something that I kind of pride myself on, being there right to the end of the matches.”