Qatar, Feb. 18 -- Novak Djokovic said the partnership with Andy Murray as his coach will continue "indefinitely". Three-time major winner Murray started working with his long-time playing rival on a trial basis at January's Australian Open, where Djokovic reached the semi-finals but was forced to retire with a leg injury, the BBC reported. After his Melbourne exit, the 24-time Grand Slam champion said he and Murray would need to "cool off" before discussing the future. However, speaking on his return to competition at the Qatar Open, Djokovic confirmed the pair will continue working together. "I expressed my desire to continue the collaboration with him, so I am really glad he did accept," Djokovic, 37, told the ATP Tour's in-house media ch...