He then drew boos from the crowd when he hit the ball away in frustration after losing that set.In his on-court interview, he apologised for what he called "the outbursts, the meltdowns"."I had a few of those today," he said.Djokovic, who is renowned for his mastery of baseline tennis, also said he opted to play more at the net than usual after repeatedly being outplayed in long rallies by Safiullin."I don't get to feel inferior from the back of court with too many players, to be honest, throughout my career," Djokovic said And it worked."He quickly seized control in the fourth set by jumping out to a 3-0 lead, and then served out the match at love.Djokovic will next face third-seeded Felix Auger-Aliassime, who came through a five-setter against No