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  Of his first 30 matches in 2017, the world number one has won 21 and lost nine.
  Winning his last five tournaments of 2016 to pip Novak Djokovic to the year-end number one position in the final match of the season at London's O2 Arena was astonishing, dramatic and unforgettable.
  And yet it appears that relentless run of success, and the 87 matches he played over a season, has come at a price.
  Murray's straight-set defeat by world number 90 Jordan Thompson in the first round at Queen's Club was the sixth time he has lost to a player outside the top 20 this year. He has had shingles and an elbow problem, and now his left hip is proving cause for concern.
  Opting out of two scheduled exhibition matches at the Hurlingham Club in London may not be too much of a blow, as Murray's aptitude for grass is likely to allow him some margin for error during the opening week at Wimbledon. But will he be in pain, and will his movement suffer?
  Although it was reassuring to see him return to the practice courts on Friday, Murray was walking with a limp and neither moving, nor hitting his backhand, anywhere near as well as he will need to. Only time will tell.
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  Murray has looked especially vulnerable this season over three sets.
  As well as the defeat by Thompson at Queen's, he has also lost in straight sets to Fabio Fognini in Rome (no disgrace), to Borna Coric in Madrid, and to world number 129 Vasek Pospisil at Indian Wells.
  Though he was bamboozled by Mischa Zverev in the fourth round of the Australian Open, his Grand Slam record remains formidable. He is aiming this fortnight for a 10th consecutive Wimbledon quarter-final, and the last time he failed to reach the second week of a Slam was when he fell to Stan Wawrinka in the third round of the 2010 US Open.
  So, assuming Murray's hip does not leave him underpowered, the French Open provides the best indication as to how he might fare at Wimbledon.
  Murray often started slowly in matches at Roland Garros, but put in a dominant third-round performance against Juan Martin del Potro as he won in straight sets. He never looked a realistic champion, but ultimately was just a tie-break away from a second consecutive final. He then ran out of steam, a legacy of insufficient matches, in a Stan Wawrinka-dominated final set of their semi-final.
  It would be foolish to try to come to a firm conclusion about Murray's chances at the All England Club this year. Twice a champion, and a gold-medal winner on Centre Court at the 2012 Olympics, not even Novak Djokovic has outperformed him at Wimbledon over the past five years.
  Yet on 2017 results alone, Murray is only the seventh best player in the field.
  He has too frequently struggled to impose himself on his opponent, and hindered at times by injury, has not been able to trust his serve in the same way.
  This year he has won 72% of points on first serve, down from 76% last year; and while last year he saved 66% of the break points he faced, that number has fallen this year to 54%.
  He claims his indifferent form is nothing to do with the pressure associated with his status as world number one, and he does not cut the figure of a man weighed down by an unwelcome burden.
  But perhaps Murray has lost his cause: he is now the hunted, rather than the hunter.
  That may not be a concern much longer.
  Murray is virtually 5,000 points behind Rafael Nadal in the season-long race and is therefore very likely to be replaced at the top of the rankings by the autumn at the latest.
  In fact, he could be overtaken after Wimbledon by Wawrinka or Djokovic if they win the title, but more probably by Nadal, who assuming both reach the second week would only have to go one round further.
  Nadal's knees, Djokovic's blues and Wawrinka's unexceptional Wimbledon record muddy the waters still further.
  And then there's Roger Federer: the seven-time champion, who is free of injuries, and last Sunday in Halle won his fourth title of the year having skipped the clay-court season.
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