Murray, 32, will play doubles with Spain's Feliciano Lopez at Queen's on Wednesday.

The three-time Grand Slam champion had planned to retire because of hip pain, before having an operation in January.

"I didn't expect to be in this position," the Scot said.

"I didn't know how it would feel if I went and had the operation. But it has been brilliant, completely life-changing for me from where I was.

"I'm looking forward to getting back out there, but I don't know what to expect and I'm not putting any kind of expectations on myself.

"Just being out on the tennis court and being pain free is enough."

At the Australian Open in January, an emotional Murray said he planned to retire after Wimbledon because he had been suffering "too much pain for about 20 months".

He also feared the opening Grand Slam of the year in Melbourne, where he lost in the opening round to Spain's Roberto Bautista Agut, would be the last tournament of his illustrious career.

Murray said the pain had made it difficult to play with his two children and do basic everyday tasks like putting on his socks.

But he says he is now pain free after having the hip resurfacing operation - which keeps more of the damaged bone than a hip replacement, smoothing the ball down and covering it with a metal cap - in London on 28 January.

Now the former world number one is back on court alongside 37-year-old Lopez, saying his priority is simply enjoying the sport which has brought him two Wimbledon titles, a US Open crown and two Olympic gold medals.

"There have been a number of times over the past 18 months where I did want to stop. I was getting no enjoyment out of tennis at all, whether that be training, practice, matches," he said.

"I wasn't bothered about winning matches either because it wasn't fun.

"Now I like playing tennis, getting out on the court and hitting balls. I want to keep playing if I can because I enjoy it.

"It would be nice to be winning Wimbledon and other major tournaments but hardly anyone gets the opportunity to do that.

"There are loads of players and it is still about having the love and enjoyment for the sport without being able to win the biggest competitions. I would hope I would be able to deal with that absolutely fine."

Murray also hopes to play in the Wimbledon doubles next month, although he has not said who he will play with.

Asked if he could win the doubles, he said: "It is possible, but it doesn't matter either way. I'd like to but it doesn't matter if I don't.

"I'd say it is unlikely because I've not played many matches."

Murray has said he will not play alongside older brother Jamie, who has linked up with fellow Briton Neal Skupski.

Andy and brother Jamie Murray have teamed up on the doubles court for Davis Cup matches and exhibitions