It was hidden at the end of a long answer about motivational issues, almost a throwaway line, but as the Scot

discussed his recent problems in the build-up to the French Open, he admitted for the first time that the effort of reaching world

No 1 may have had a bigger effect than previously thought.

Twelve months after reaching the final here, Murray cut a frustrated figure as he outlined the three viral illnesses he has suffered in 2017, which stopped his momentum abruptly in its tracks. Throw in the elbow injury that forced him out of the Miami Masters and interrupted his preparations for the clay-court season and his early exits from Monte Carlo, Madrid and Rome can be explained.

He reached the semi-finals in Barcelona but what is harder to explain away is the appearance, at least, that in Madrid and Rome, when the chips were down, his heart was not in it.

“I was asked a question at the end of last year . . . and it happens a lot in sport when if you achieve something quite big, it can be quite natural to maybe struggle for a few months,” Murray said. “I have been training as well as I could the last few months. Just maybe in a couple of matches it’s just been a little bit flat.

“When I won Wimbledon the first time, I felt like that (to try to win it) was why I was playing, really. I had achieved my biggest goal. You feel a bit lost afterwards. You need to then reset your goals and maybe at times there has been a little bit of that.”

One of Murray’s former coaches, Miles Maclagan, believes the Scot spent so much energy chasing down Novak Djokovic at the top of the rankings that he had nothing left at the start of 2017, when he was beaten in the Australian Open third round.

“I think we maybe underestimated how tough it was and how tough it is to achieve what they’re doing,” said Maclagan, who will be working for Eurosport at the French Open. “For Andy, it’s very rare that players of that quality experience something new and perhaps being No 1 and having the pressure on him is a new experience that he’s finding difficult to adjust to.

“Andy’s doing the work physically, he’s doing the work on court so I do think it could slot into place any minute. It’s just a little bit of a new situation for him, being top dog and feeling a bit of pressure.

“What’s very unusual is that normally he’s the competitor, the scrapper, he finds a way to get involved, that’s obviously a mental thing because physically and game-wise I’m sure it’s all there.”

Former British No 1 Tim Henman suggested that the shingles may have lingered longer in his system than first thought.

“When I got back (from Miami), I had tests that showed I had suffered shingles,” Murray said. “Earlier in the year (after Australia) I just went to the doctor and they just looked at me to confirm it was shingles. But I did not have any tests then.

“The blood tests done showed everything else was fine. I did have tests for glandular fever and got the all-clear. It’s been frustrating . . . but I want to get through this. I know I will. I just don’t know when. But I hope it’s in a few days.” Murray has been training in Paris under the eye of Ivan Lendl, who flew in last weekend – as had always been the plan – who is back alongside him for the first time since Melbourne.

Murray, who turned 30 this month, said he would draw confidence from Lendl’s presence, although he was quick to point that the former world No 1 was far from a frequent companion in the second half of 2016.

Maclagan believes one match could be enough to get him back on track while the return of Lendl could be key.

“Having someone of that stature to say I went through that, maybe that’s the catalyst,” he said. “(If) he can get through the first week and then things can settle into place. He can put a different perspective on it and say look, enjoy this pressure.”

Murray’s mood may have been buoyed by the draw for the French Open, which put him in the other half to the two biggest guns of all on clay, nine-times champion Rafael Nadal and defending champion Novak Djokovic.

Stan Wawrinka is his scheduled opponent in the semi-final but given his poor form – and the remnants of a cough – he will be focusing only on getting past Andrey Kuznetsov, a Russian ranked 85, whom he has beaten in two previous meetings. “At the start of this year he has struggled a little bit,” Murray said. “But the last few weeks he’s been winning. He (was) in the semis of Geneva against Stan (Wawrinka) and . . .he’s made improvements. It’s a good first match.”

Murray believes he will back on track soon but after Kuznetsov, he will have to hit form quickly with Juan Martin Del Potro a possible third-round opponent and German Dominic Thiem a winner in Rome, likely to be waiting in the quarter-finals.