John McEnroe believes Grand Slam glory has ‘overwhelmed’ Emma Raducanu (Pictures: Getty)

John McEnroe believes Emma Raducanu has been ‘overwhelmed’ by her remarkable Grand Slam win and slammed the ‘unbelievable’ decision to change coaches after her French Open exit.

Raducanu became the first qualifier in history to win a major and ended Great Britain’s 44-year wait for a women’s Grand Slam singles champion at the US Open last year.

Since her fairytale run in New York, Raducanu has suffered second-round defeats in consecutive Grand Slams, with the 19-year-old struggling to replicate the heroics that saw her triumph at Flushing Meadows.

The British number one split with Andrew Richardson after her US Open win and then dispensed with Torben Beltz ahead of the clay court season.

American tennis legend McEnroe, who won seven Grand Slams, says the ‘revolving door of coaches’ has hampered Raducanu’s development.

The 63-year-old told Eurosport: ‘Honestly, if I won the US Open having gone through qualifying, I wouldn’t change my coach at least for the next year, so I don’t understand that move.

‘Obviously her parents are involved and they know more than I know. But this idea of a revolving door of coaches I just don’t think that’s good for any player, much less so for a player at this stage of her career.

Raducanu enjoyed a fairytale run at last year’s US Open (Picture: Getty)

‘We have to wait and see and hopefully she finds someone she can stick with for a while. She has changed coaches, three, four or five times which is unbelievable for someone who has just come off winning a major.’

McEnroe, who was critical of Raducanu after she withdrew from her fourth-round match at Wimbledon last year, also believes the Brit is struggling to cope with the ‘expectation’ of being a major winner.

‘We have got to keep a little perspective here,’ he added. ‘At Wimbledon last year she was unable to finish a match because of stress and it got to be too much for her.

‘Then she came out and did something that no one has ever done – man or woman – in 150 years of tennis, coming from the qualifying and winning.

Raducanu has failed to reach the third round in the last two Grand Slams (Picture: AFP)

‘All of a sudden, there is this pressure on her, this expectation, that has gotten a little bit overwhelming as well.

‘I think movement is an issue for her, obviously experience, she is still very young. She has sort of put herself in a difficult position because a lot is expected of her and with the people around her, we are not sure if she is comfortable with them just yet. Hopefully in the next year or two she will find that.’

Raducanu faced Aliaksandra Sasnovich of Belarus in the second round of the French Open and took the first set 6-3 before winning just two more games and crashing out.

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She was keen to take the positives from her clay-court campaign, however, telling reporters: ‘I’m quite happy with the progress that I’m making.

‘I do feel like I’m playing some pretty good tennis and on the practice court I’m definitely working. Certain things I’m working on on the practice court that are paying off, they don’t show immediately.

‘There is a little time lag between when they will actually produce results on a live situation. I’m definitely getting there.’

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