Andy Murray said he was suffering from cramp and fatigue following his last-16 loss to world number 240 Matteo Viola at the Rafa Nadal Open.

Former world number one and three-time grand slam champion Murray struggled physically as he went down 3-6 6-4 7-6 (7-3) at the ATP Challenger event in Mallorca on Thursday.

Murray dropped down to the Challenger Tour for the first time since 2005 in a bid to improve his fitness following hip resurfacing surgery in January, which threatened to end his stellar career.

After blitzing teenager Imran Sibille and overcoming third seed Norbert Gombos, the 32-year-old Murray succumbed to Viola in a third-set tie-break.

"I'm cramping. Very tired," said Murray, who required a medical timeout midway through the third set, after almost three hours on court.

"I would have liked to have played more matches but it was good. I played two competitive matches. Physically I need to get better."

Murray is featuring on the Challenger Tour for the first time in 14 years.

The Brit started a singles comeback at ATP Masters 1000 tournament the Western & Southern Open before making a swift exit from the Winston-Salem Open.

Murray – who played a series of high-profile doubles tournaments after teaming up with Serena Williams in the mixed event at Wimbledon – then opted to skip the US Open in New York.

Rafael Nadal revealed he had offered his boat to Andy Murray while the Brit plays at the ATP Challenger Tour event in Mallorca.

Murray's singles comeback is gathering pace and he moved into the last 16 at the Rafa Nadal Open on Tuesday.

Nadal, meanwhile, eased past John Millman to improve to 15-0 in first-round matches at the US Open.

The Spaniard said he had been in touch with Murray to offer any help, and the use of his boat, while he plays in Mallorca.

"I think he used it already in the past, no? I just text him when I knew that he was going to play at the academy," Nadal told a news conference.

"I just text him a couple of days ago saying, 'if you need anything, just let me know. You want to go out with the boat or anything, I can help you, just let me know'.

"For us in the academy, it is great news that he's there, of course. I saw the court yesterday where he was playing, it was full crowded. I think it's great for him, great for us.

"For me personally, as I said a couple of times, happy for him. Honestly he did a lot of things to try to be back on court and keep playing tennis.

"The decision to go and play a Challenger is because he feels well, my feeling, the way that I see it. If you don't feel it very well, you play normal tour and just let's see how it goes.

"If one player like Andy is able to go and play a Challenger it's because physically he feels well and he wants to play matches."

Nadal crushed Millman 6-3 6-2 6-2 in the US Open first round on a day that saw multiple upsets in his half of the draw.

Dominic Thiem, Stefanos Tsitsipas, Karen Khachanov and Roberto Bautista Agut all made first-round exits.

"That's tennis. That's all the reaction I can say, no?" said Nadal, who will face Thanasi Kokkinakis in the second round.

"When you start the tournament, you have difficult opponents in front. You need to go on court and respect every single opponent.

"I went on court today against a tough opponent knowing that I need to play well to win. If you play bad, you can lose.

"Tsitsipas had a very tough first round. Of course, Karen is a surprise. I think Thiem have been very sick for the last 10 days. I feel very sorry for him.

"Roberto was a surprise. Honestly, I'm very sad for him."

Andy Murray said he was happy with his performance after defeating third seed Norbert Gombos at the Rafa Nadal Open as the three-time grand slam champion's singles comeback continued.

Murray advanced to the round of 16 in Mallorca, where the former world number one overcame Gombos 6-3 6-4 on Tuesday.

The 32-year-old Murray dropped down to the ATP Challenger Tour for the first time since 2005 in a bid to improve his fitness following hip resurfacing surgery in January, which threatened to end his stellar career.

After blitzing teenager Imran Sibille in his opener, Murray upstaged Gombos – who leads the Challenger circuit for match wins with a 36-16 record.

"I think I did well, it was a tough match," said Murray. "He hits his shots very hard, so I had to do quite a lot of moving and defending.

"There are things I'd like to do better, but it was a good match.

"I don't play tomorrow [Wednesday], so that's nice to get a day to rest and recover. That's important at this stage of my comeback."

Murray, who will face world number 240 Matteo Viola for a place in the quarter-finals, is featuring on the Challenger Tour for the first time in 14 years.

The Brit started a singles comeback at ATP Masters 1000 tournament the Western & Southern Open before making a swift exit from the Winston-Salem Open.

Murray – who played a series of high-profile doubles tournaments after teaming up with Serena Williams in the mixed event at Wimbledon – then opted to skip the US Open in New York.

Andy Murray continued his singles comeback via the ATP Challenger Tour with a straight-sets win over Norbert Gombos at the Rafa Nadal Open.

Former world number one Murray reached the last 16 of the event thanks to Tuesday's 6-3 6-4 victory against third seed Gombos in Mallorca.

Murray dropped down to the Challenger Tour for the first time since 2005 in a bid to improve his fitness following hip resurfacing surgery in January, which threatened to end his stellar career.

The three-time grand slam champion started a singles comeback at ATP Masters 1000 tournament the Western & Southern Open before making a swift exit from the Winston-Salem Open.

Murray – who played a series of high-profile doubles tournaments after teaming up with Serena Williams in the mixed event at Wimbledon – then opted to skip the US Open in New York.

The 32-year-old turned to the Challenger Tour for the first time in 14 years, and after blitzing teenager Imran Sibille in his tournament opener, Murray saw off Gombos.

Gombos provided a much sterner test for Murray, who needed almost two hours to beat the Slovakian world number 115.

Murray will next face world number 240 Matteo Viola for a place in the quarter-finals.

Andy Murray's return to the ATP Challenger Tour lasted just 43 minutes and 13 games as he thrashed teenager Imran Sibille at the Rafa Nadal Open.

A 6-0 6-1 success on Monday handed Murray his first singles win since returning from injury.

The former world number one has been building his fitness following hip resurfacing surgery in January that he believed would end his outstanding career.

The Briton recovered to play a series of high-profile doubles tournaments - including alongside Serena Williams in the mixed event at Wimbledon - before trying his hand back on the singles court.

But Murray, ranked 328th, has found it tough back on the regular ATP Tour circuit, losing in straight sets to both Richard Gasquet and Tennys Sandgren.

The 32-year-old therefore made the decision to return to the Challenger Tour for the first time in 14 years, featuring at the Rafa Nadal Open while his peers - including Rafael Nadal - play the US Open.

If Murray is to rediscover his best form, he will hope for sterner tests than that he faced from Sibille, though, who was dismantled with ease.

Just three points went the 17-year-old's way in the opener, with Murray only denied a double-bagel victory in the Frenchman's final service game of the second.

His next task in Mallorca is against Norbert Gombos, the third seed, on Tuesday.

Andy Murray will play on the ATP Challenger Tour for the first time in almost 14 years after accepting an invitation to next week's Rafa Nadal Open.

Former world number one Murray will travel to Mallorca and appear on the second-tier circuit for the first time since reaching the quarter-finals at Mons in October 2005.

The three-time grand slam champion underwent surgery to overcome a career-threatening hip injury and made his return after five months out in the doubles at the Queen's Club Championships in June, lifting the title alongside Feliciano Lopez.

Murray made his singles comeback at the Western & Southern Open in Cincinnati last week, losing to Richard Gasquet in straight sets.

The Briton, who has signed up to main-tour events in Zhuhai and Beijing in September and Antwerp in October, has slipped to 329th in the world rankings and rejected a wildcard to the US Open.

Following a first-round loss to Tennys Sandgren at the Winston-Salem Open this week, Murray explained he was considering dropping down to the Challenger Tour in a bid to improve his singles level.

"Some things were a bit better [against Sandgren], I think," he said. "I was hitting the ball a bit cleaner than I did maybe in Cincinnati.

"I feel like I moved fairly well to some drop shots, which maybe last week I wasn't running to. So there's some good things in there but also some stuff I would like to do better.

"I'm physically okay considering, no pain, no discomfort. Just a little bit more tired than usual.

"I'm quite aware of sort of where I'm at just now and what my level is. It's competitive at this level but it needs to be better.

"Maybe I need to play a level down to get some matches and build my game up a little bit before I start playing on the (main) tour again."

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