Dubai Tennis Championships: Top-ranked Novak Djokovic, Stefanos Tsitsipas reach quarter-finals with easy wins

File image of Novak Djokovic. AP Photo[/caption]Djokovic broke for a 4-2 lead in the first set and went 4-0 up in the second before wrapping up the win in 59 minutes. The Serb is 15-0 this year, including six wins at the ATP Cup and his run to the Australian Open title.“It was a great performance,” Djokovic said. “I enjoyed the way I played, coming out with the right focus and tactics.”Djokovic will next face seventh-seeded Karen Khachanov of Russia, who beat Austrian qualifier Dennis Novak 6-3, 6-4.Second-seeded Stefanos Tsitsipas defeated Alexander Bublik 7-6(1), 6-4 to set up a meeting with Jan-Lennard Struff, who needed just 39 minutes to ease past Nikoloz Basilashvili 6-1, 6-0.Third-seeded Gael Monfils of France took his winning streak to 11 matches by ousting qualifier Yasutaka Uchiyama 6-1, 6-2. Monfils is coming off victories at Rotterdam and Montpellier.He will face fellow Frenchman Richard Gasquet, who ousted No. 8 Benoit Paire 6-4, 6-4.