Andy Murray has announced his split with coach Ivan Lendl, with the pair mutually agreeing to end their relationship.
Murray's recent stint with Lendl was their second together, the first having seen Murray win the US Open, Wimbledon and the first of his two Olympic gold medals.
Lendl resumed his role as Murray's coach in June last year following the Briton's split with Amelie Mauresmo.
He won the Wimbledon and a second Olympic gold, but his 2017 season was severely hampered by injuries.
Murray lost in the fourth round of the Australian Open to Mischa Zverev but did reach the semi-finals of the French Open, only to be beaten by Stan Wawrinka in five sets.
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The 30-year-old was significantly affected by a hip injury at Wimbledon and a quarter-final defeat to Sam Querrey proved his last match of the year, with Murray losing his number-one ranking and missing the US Open as a result of his lay-off.
Murray, who will continue his efforts to get back to fitness in Miami before heading to Australia to prepare for the opening grand slam of 2018, said: "I'm thankful to Ivan for all his help and guidance over the years, we've had great success and learned a lot as a team.
"My focus now is on getting ready for Australia with the team I have in place and getting back to competing."
Lendl added: "I wish Andy well going forward. We had a great run and a lot of fun."
Murray has dropped to 16th in the world rankings in his time off the court, but will hope his time away will prove to be a blessing.
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Roger Federer and Rafael Nadal both benefited from extended absences and greater management of their schedules in 2017. Federer won the Australian Open and Wimbledon while Nadal triumphed at the French Open and the US Open.
Novak Djokovic, having struggled with an elbow injury in 2017, has also not played since Wimbledon, dropping to 12th in the rankings, though he has decided Andre Agassi will remain his coach in 2018.
Murray and Djokovic's respective slide down the rankings sets up some potentially fascinating first-week matches at the Australian Open, which starts in Melbourne on January 15.