MONACO — Top-ranked Novak Djokovic overcame a strong challenge from Rafael Nadal to reach the Monte Carlo Masters final with a 6-3, 6-3 win Saturday.Djokovic, who extended his current winning streak to 16 matches, will face sixth-seeded Tomas Berdych as he bids for a second title at the clay-court Masters.With Prince Albert of Monaco among the onlookers, both players produced some stunning tennis in the semifinal as Nadal showed glimpses of his old self, mixing aggression and superb defensive shots.But the Spaniard, who has been struggling to get back to his best after a wrist injury and an appendectomy, was not consistent enough to deny Djokovic a shot at his fourth Masters title in a row.Following his title at the Paris Masters last year, Djokovic posted back-to-back victories at Indian Wells and Miami and will try to become the first player to win the first three Masters of the season.Nadal will rue his missed chances in the seventh game of the opening set, when he was unable to seize the momentum after a stunning forehand down the line that wrongfooted the Serb.