Former US Open champion Andy Murray admits cramping issues are 'concerning' after sweat tests come back clear

Andy Murray remains unsure of the cause of his persistent cramping issues after undergoing sweat tests.

Murray confirmed that the tests ruled out illness, but did not provide a solution. He said: "The sweat test was good, blood test was good. No illnesses. I know now it is down to conditioning, hydration or food related. That is something I can obviously control a little bit as well."

The former world No. 1 has been struggling with hot and humid conditions during the North American hard court swing.

He admitted confusion as to why he has been facing this issue, saying: "I feel like I am in decent shape so that it is why it is concerning. I don't really know why it has happened. Last few days in practice I have actually felt a bit better in the conditions and everything so hopefully I will be alright on Monday."

In his recent Cincinnati Masters third round defeat to fellow Brit Cameron Norrie, Murray started well - winning the first set - before beginning to struggle physically.

After the match, Murray said: "It's a big concern for me, it's something I need to address and find a solution for. No-one knows exactly why cramps happen. There are many reasons, whether it's hydration, food, fatigue, lack of conditioning, stress. You need to try to understand what's going on there."

Murray admitted that the emergence of the cramping issue was vexing, after undergoing numerous other physical trials in recent years, saying: "it is a bit frustrating right now because I am in a much better place physically in terms of my left groin and lower back but I've been having the cramping these last few weeks."

While this has been his most productive year since 2016 - he has played more matches this year than any year since then and has a 23-15 record - there have also been numerous frustrating setbacks for Murray. The abdominal injury suffered in Stuttgart slowed him down, and now the cramping issue threatens to hurt his US Open campaign.

The emerging problem threatens to remove one of Murray's key attributes, his dogged refusal to be beaten and to grind out results over five sets.

The 2012 champion returns to Flushing Meadows, where he has not won more than one match since 2016.

He begins his campaign this year against Argentinean world No. 27 Francisco Cerundolo, an opponent more than 10 years his junior. It will be their first ever meeting on the main tour.

Upon confirmation of his opponent, Murray was positive, saying: "it's not the worst draw I could have had, but there are also better draws out there as well. Cerundolo is a young guy but is in the top 30 in the world. It's kind of his first full year on tour, but he won a tournament a few weeks ago and made the semis in Miami earlier this year. He's going to be improving all the time because of his age, so it's not an easy match for me to start off with, but I also could have played Daniel Medvedev in the first round. I've prepared as well as I could this week."