Cameron Norrie admits to nerves during his three-set win over a struggling Andy Murray at the Cincinnati Open

Cameron Norrie said that his positive attitude helped him seal his first-ever win over British compatriot Andy Murray at the Cincinnati Open.

Norrie’s 3-6 6-3 6-4 win in 2h37 was not one of his better performances, with the 35-year-old Murray in the ascendancy for much of the match.

But Norrie never wavered mentally, and he admitted afterwards that was the key as he ground down Murray, who ended the match unable to walk due to cramps, a problem that has been his bete noire during the US hard-court season so far, and that saw him helped off the court at the finish.

Speaking to Prime Video, British No. 1 Norrie said: “I think it just came down to a little bit of physicality.

“It probably didn’t help him [Murray] that his match with Stan [Wawrinka in the first round] went really long.

“I got through with my attitude and tried to stay as positive as I could.

“Nothing was really working for me at all and I found myself at one-set all I don’t know how. I was looking really slow and not moving well but I managed to do that better and better as the match went on.

“Maybe it was a little bit to do with nerves. When you’re feeling tight the feet are the first thing you struggle to work. That’s how it rolls with tennis, hopefully I can keep improving. It’s a massive win for me.”

For a player so up against it on paper – not just by ranking but also due to that marathon Wawrinka match – Murray compounded the difficulty of his task by dropping his opening service game.

A shank and a let chord played their part in Norrie getting the break, but Murray just looked a little short of intensity at the start.

A couple of lung-busting rallies perhaps dispelled any notion of a physical hangover from the previous round, and Murray chalked up an immediate chance to break straight back – which he took after Norrie had dumped consecutive forehands tamely into the net.

Murray seemed to be growing into the encounter, and he yelled a loud “come on!” as he held in game three to take a 2-1 lead at the sit-down.

The Scot then brought up two more break points in the next game, but Norrie saved the first after a 28-shot exchange and then fired in an unreturnable serve on the next.

He then worked Murray over in the next two points – using the drop shot to good effect – to rescue a fine hold from 15-40 down.

Murray was hitting his forehand 8mph faster than in his win over Wawrinka, and he was needing to in order to unsettle the indefatigable Norrie. Both players whistled through their next service games to make it 3-3, and it was growing harder to predict which way the first set would tip.

But then came the turning point, as Murray broke to lead 5-3. The tactics were clear for the Scot, attacking the net behind his heavier groundstrokes, slicing into the flat Norrie backhand with sustained success and keeping the points short in the quick conditions.

And he was able to avoid any danger as he served out the set, taking it 6-3.

Could he front-run effectively against his compatriot and – against the bulk of the pre-match predictions – take the match in straights?

The early signs were promising as he forced a break point in the very first game, but he was unable to secure it after a botched volley right on top of the net.

Norrie was mixing up his game plan in a bid to find a route back into the encounter, but he couldn’t generate any openings of his own on Murray’s serve and he had some thinking to do at the changeover, with the score 3-2 to the 26-year-old on serve.

But alas suddenly Norrie did force a break point as play resumed, with Murray slamming his racket against his shoe in annoyance at his mistakes.

The two-time Cincy champ recovered however, serving a couple of big kickers which forced Norrie to go long on that point, and then again on game point as Murray levelled at 3-3.

Norrie raced through his next and the pressure was once again on Murray, with the Scot just beginning to show signs of frustration, chuntering at what he felt was an incorrect line call and being faced with another break point after Norrie found a terrific short-angled backhand.

This time the world No. 11 did take his chance, going 5-3 ahead and with a chance to level the match on his serve.

However Murray had no intention of accepting his fate, generating three break points as Norrie slipped to 0-40.

But Norrie rebounded in style, sealing the game – and the set – with two aces.

As it went into a decider, Murray would surely have been rueing that missed volley from the first game in set two, and he got on the board first in the first game of set three with a battling hold.

But Norrie – who levelled it up at 1-1 without undue bother – was looking more and more comfortable, drawing Murray into longer and longer rallies and looking the fresher as the match went on.

Murray did at least record a simpler hold to lead 2-1 at the first sit-down. As the match ticked past two hours, could the 35-year-old find a second wind to down the resurgent Norrie?

He came mighty close in game five, but it was a case of deja-vu for the Scot as he fluffed an easy forehand putaway – and a series of break points – before Norrie hit two aces to get out of the game unscathed.

Murray put that disappointment out of his head to move ahead 4-3 and that became 4-4 as Norrie – once again – served his way out a spot of bother at deuce.

But the heat – and match duration – were beginning to take its toll on Murray, and the cramping that has affected him during the US hard-court season struck again as Murray surrendered, handing Norrie the break and the chance to serve it out.

Outlasting opponents physically was what Murray did so expertly in his prime but it felt like the opposite here, with Norrie looking like he could go another two hours.

But he only needed another few minutes, sealing his victory in 2h37.

For Murray, it ended in ignominy as he could barely walk on the final point and had to have a massage on his thigh just so he could get off the court.

The positives will be that he was the better player tennis-wise and that he pushed Norrie much closer than many expected.

Physical conditioning, as always in recent times, and an ability to take his chances – he only took two of eleven break points during the match – will be the issues to solve prior to the US Open.