LONDON, United Kingdom (AFP) — Andy Murray will no longer be coaching former rival Novak Djokovic, ending their six-month partnership, the pair announced Tuesday.

Djokovic stunned the tennis world in November when he said he had hired the retired Murray, who had no track record as a coach, to lead his off-court team.

But the two 37-year-olds have already parted company, with Britain’s Murray thanking Serbia star Djokovic for an “unbelievable opportunity.”

Their split comes after Djokovic, the winner of a record 24 men’s Grand Slam singles titles, endured a difficult start to the season — including losing his first match at his last two tournaments.

“Thanks to Novak for the unbelievable opportunity to work together and thanks to his team for all their hard work over the past six months,” Murray said in a statement.

“I wish Novak all the best for the rest of the season,” added the Scot, who defeated Djokovic in the 2012 US Open and 2013 Wimbledon finals to win two of his three Grand Slam titles.

Their partnership started well, with Djokovic defeating Carlos Alcaraz at the Australian Open, only to retire through injury during his semi-final against Alexander Zverev.