Caroline Wozniacki moved a step closer to erasing an unwanted footnote from the list of her tennis achievements with victory over Svetlana Kuznetsova in the French Open fourth round on Sunday.Wozniacki is that rare beast: a twice year-end world number one-ranked tennis player who has never won a grand slam.There have been others but none who reigned so long at world number one – 67 weeks – without success on the grand slam stage.On Sunday the Dane beat Kuznetsova, a player with two grand slam titles in the bag but who has never scaled the women’s rankings to the very top.The 6-1 4-6 6-2 victory eased Wozniacki into the quarter-finals at Roland Garros, matching her best performance here in 2010.”Obviously it’s just kind of clicking this week,” Wozniacki smiled as she spoke to reporters. “Hopefully I can keep going this way. Now I just try and stay focused and keep my headdown.”Wozniacki streaked into the lead on a sun-baked Philippe Chatrier court, running away with the first set as 2009 champion Kuznetsova struggled with her range.Eighth seed Kuznetsova soon struck back to level matters, using her weight of shot to overpower the Dane.Kuznetsova was always likely to hit the big winners but they were too few, and errors more plentiful, as Wozniacki grabbed two early breaks in the decider.The 11th seed, her luminous green racquet a rapier to Kuznetsova’s broadsword, eased into a 3-0 lead but after a few meaty swings Kuznetsova broke back.advertisementIt was only a temporary reprieve for the Russian, though, and Wozniacki reasserted her control, pummelling a two-fisted backhand down the line to win the match, before firing a ball into the upper tier of the stands.”Yeah, it was definitely a good win,” she said. “Svetlana obviously plays really well on this surface. I knew it was going to be a tough match going in.”I started off really, really well. My game plan was working and kind of kept her on her toes with putting in some dropshots and mixing up the pace.”I knew it wasn’t going to be easy. I knew that she was going to try to fight her way back. She did in the second set, but I managed to close it off in three, which I’m happy about.”Wozniacki next faces either 2010 runner-up Sam Stosur or Jelena Ostapenko for a spot in the semi-finals.”Definitely two tough opponents, two very different opponents. Sam loves the clay. She’s had great results here in the past.”Either one is going to be tough. Ostapenko goes for her shots and plays flat. When she’s on fire, she’s tough.”Tough or not, the dazzlingly white smile is back on Wozniacki’s face, and without the pregnant Serena Williams and the missing Maria Sharapova in the draw, she might just be ready to erase that asterisk next to her name.