MELBOURNE : Novak Djokovic continued his charge towards a 10th Australian Open title with a superb 7-6(7) 6-3 6-4 victrory over Bulgarian Grigor Dimitrov to reach the fourth round on Saturday but fears about the durability of his injured left hamstring only grew.The Serbian, who is eyeing a 22nd major to match Rafa Nadal, said he felt "up and down" physically during the three hours and seven minutes he was on court as Dimitrov searched in vain for his second win over the fourth seed in their 11th meeting.Fourth seed Djokovic looked uncertain in his movement during a roller-coaster first set where he began with a break, squandered three set points at 5-3 and dropped serve late on before edging a thrilling tiebreak."Well it (the tiebreak) was as important as any other game.
But I think that probably was one of the most important moments in the match," Djokovic told reporters."To prevail in the tiebreak and get a set ahead.
Being a set down or a set up is a big difference. Mentally and physically... Kind of went up and down feeling physically with my leg."I just found a way to win in such an exciting match, big battle, over three hours for three sets.
If I lost one of these sets, we could have gone the distance. God knows how long."We already had some matches over five hours during this tournament.