Last summer Murray became the first British man to win Wimbledon in 77 years, but the 27-year-old has not reached a final since then.

There have been two major upheavals in his career since that heady Sunday afternoon in SW19 - back surgery last September and a split with coach Ivan Lendl in March.

This is a Murray we were familiar with a few years ago - a set full of ups and downs, opportunities for his opponent, a mixture of mistakes and brilliant winners. Two break points come and go for Haase before Murray, under pressure at the baseline, screws a forehand wide on the third break point.

Piers Newbery
BBC Sport at Flushing Meadows

The Louis Armstrong Stadium has not always been Murray's favourite hunting ground - the last time he lost before the quarter-finals at a Slam was on the same court against Stan Wawrinka in 2010.

Image source, Getty Images

Houston, we have a tennis match on our hands. The world number 70 now seems more comfortably in his surrounding. No longer is he seeing headlamps and hearing sirens. A trouble-free hold to 15 and the Dutchman is in front once more.

Nick Bollettieri
American tennis coach on BBC Radio 5 live sports extra

"Haase has a big first serve and if that starts clicking and Murray's serve flutters, this match could get interesting. I wouldn't give Murray more than a six for the first set. He's got to get much more consistent on his first serves."

Shohidur Rahman:, external The serve is a big problem for Murray in terms of how inconsistent he is with it. When he goes big he can't get it in.

Andrew Priestley:, external Andy Murray is going into this year's US Open as the 'lowly' Number 8 seed & with low expectations. It could work in his favour.

Alana Bardill:, external Nick Bollettieri has a great voice that wouldn't be out of place in a gangster film!

Murray, dressed in grey and black but with radioactive green trainers adding a splash of colour to his outfit, is far from the swashbuckling superhero who destroyed Haase in the opening four games of this match. But even with his superpowers not firing on all cylinders, the Scot, you sense, has too much in his armoury for his opponent. A brilliant crosscourt forehand winner from Murray and we're level.

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Murray versus Haase is a rematch of their 2011 second-round ding-dong which the Scot won, although he had to claw his way back from a two-set deficit to see off the right-hander.

If head-to-head records is your thing, then perhaps you'll react enthusiastically when I tell you that this is the pair's fourth encounter. Murray enjoys a slightly superior record, winning two of their three matches.

A much better start for Haase in this set as he races to a 40-0 lead. A serve out wide, which Murray returns into the net, secures him the opening game.

David Law
BBC Radio 5 live sports extra commentator

"Murray clenches his fist as he wins the first set - he's a much better player when he erupts with emotion like that. At times, this has been too much like a practice session from Murray - just duking it out on the baseline and not really going for his shots."

Piers Newbery
BBC Sport at Flushing Meadows

Murray's early efforts are attracting a decent crowd in Armstrong and there is the usual flow of spectator traffic and conversation throughout, something the players have to embrace here. Murray has plenty of support as the end of the set gets a bit edgier than he would have hoped. Time for a mass refreshment exit.

Murray throws in another double fault and the crowd become anxious as they look at the scorebaord and see the underdog 15-30 up. The Briton digs in under the mid-afternoon sun and has a set point but, hang on, Haase is coming back from the brink... He forces Murray on the defensive with a fabulous forehand and ends a 26-shot slug-fest with a deft volley. Deuce! Break point! A crunching return from Haase and Murray seems a little punch-drunk.

Cool head needed and Murray delivers, negotiating the danger by forcing Haase onto his heels and eventually he wraps up the set, his serve back on song and anxiety long gone.

Nick Bollettieri
American tennis coach on BBC Radio 5 live sports extra

Image source, Getty Images

"It's not a good sign that Murray is standing so far back behind the baseline. What made the difference in his game the last couple of years was that he came in and started taking the ball on the rise. Haase's not in the top 20 because of his unforced errors, but he's got a big forehand and a big serve."

Groans from the crowd as Murray fails to nail an attempted drop shot. Haase adding some oomph to his groundstrokes, easing to 40-0 with a dazzling forehand into the corner and Murray offers little resistance as the Dutchman holds.

There are a number of empty seats on Louis Armstrong, but the majority of those who have turned up seem to be cheering for Murray. The crowd favourite brings up game point with an ace and stylishly holds - taking inspiration from the NBA's ballers by floating into the air and unleashing an angry volley.

David Law
BBC Radio 5 live sports extra commentator

"Haase is looking a little bit more confident now. He does have some thunderous power in his groundstrokes, but he's a little inconsistent. Murray's standing right back with the line judges at the moment, way behind the baseline."

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No-one in this office truly knows the real Robin Haase, being that there has been no contact or communication with the Dutchman. But what I can tell you is that he's ranked 70th in the world, is 27 years old, and is a right-hander - even though he is actually left handed.

That break of serve was the nerve-easer that the Dutchman needed and he's proving to be more of a contender in this game, getting the better of Murray in a lengthy baseline rally for a 30-15 lead. But, having typed that, Haase double faults for 30-30. Errors from both players as the game progresses to deuce, but Haase eases to advantage with an ace and the game concludes with a faulty Murray forehand.

"Ooh" sing some in the crowd, pantomime-style, as Haase grabs two break points. A double fault and an iffy challenge proving to be Murray's downfall as he goes through one of his dips. The British number one trudges back to his seat during the changeover. He's still in control but there could be trouble ahead.

David Law
BBC Radio 5 live sports extra commentator

"Body language tells you everything from Haase - his shoulders are slumped and his eyebrows are raised. He's got to get himself on the board quickly, otherwise this could run away from him quickly. Murray is in a perfect position."

Murray nicks the opening two points but Haase stops the rot with a serve-volley. Murray, shoulders slumped as he comes unstuck at the net for 30-30 and this is as close as the Dutchman has got in these opening four games. But Haase approaches the net once more as confidently as a hippopotamus on ice, and Murray passes him for a break point.

To deuce we go, however.... Haase challenges a Murray forehand, which replays show hit the line so it's a second break point for the Scot. But Murray needs a third break point before sealing the deal - Haase plonking a backhand into the net to gift the Scot a perfect start.

Nick Bollettieri
American tennis coach on BBC Radio 5 live sports extra

"I'll give Andy a tip - he needs to get in close to the baseline. Haase is standing 10 feet behind. He needs some gimme points from his first serves and some defensive returns."

The sound of aircraft hovering up above in the azure sky... trainers screeching on court... one or two yelps of encouragement for the Scot from the crowd... Murray flying and the eighth seed confidently holds with a thunderous ace