Andy Murray lost 3-6, 6-3, 6-4 to fellow Brit Cam Norrie with the Scot determined to get to the bottom of the cramping issue that contributed to his second-round defeat on Wednesday at the Cincinnati Masters.

The pair played deadlocked tennis until the closing stages when Murray’s fitness began to wane and his cramping became more of a distraction.

Norrie said a few key points made the difference.

The No. 11 winner produced 39 winners to 37 for three-time Grand Slam champion Murray.  The Scot  converted on only two of his 11 break chances and contributed nearly  40 unforced errors.

“I was not physical enough at the start of the match,” Norrie said. “I was not executing the way I liked.

“All credit to Andy, it was not easy at the end but I managed to find a way. I was pleased to get through without playing my best.”

Murray explained that he has got some medical detective work ahead.

“The consistency (of the cramping over the past month) is a big concern. 

it’s not something that I have really experienced consistently over anumber of tournaments.

“it’s not easy to play when it gets bad like it was at the end,” added the player who needed a massage on court in defeat before he could walk off.

He added: “Cramping had an impact on the end of the match. It certainly affected the way that I played right at the end, , from the middle of that set. 

“At times I felt like I played really well and then at times didn’t. My consistency maybe was not where I’d want it,” Murray said.

“But there was some positive tennis in there at times. I definitely had enough opportunities to win that match.”