Serena Williams ended a difficult-for-her Grand Slam season in the best way possible, winning her third consecutive U.S. Open title by beating Caroline Wozniacki 6-3, 6-3 on Sunday.Williams equaled Chris Evert and Martina Navratilova with 18 major singles titles, the fourth-most in history. Williams also matched Evert’s total of six championships at the U.S. Open and became the first woman to win three in a row since Evert’s four-title run from 1975-78.Williams earned $4 million, a record in tennis — $3 million for the title, plus a $1 million bonus for having had the best results during the North American summer hard-court circuit.It was a dominant performance to cap a dominant two weeks in Flushing Meadows. Not only did Williams, ranked and seeded No. 1, win all 14 sets she played in the tournament, she never even dropped more than three games in any of them.Until the U.S. Open, though, Williams had not been at her best on her sport’s biggest stages in 2014. She lost in the fourth round at the Australian Open, the second round at the French Open, and the third round at Wimbledon, where a disoriented Williams also struggled through an odd appearance in doubles that was attributed to a viral illness.Back at the top of her game, Williams broke Wozniacki’s serve five times and compiled a hard-to-believe 29-4 edge in winners. Remarkably, until a cross-court backhand on the run in the final game that even Williams applauded, the only winners registered by the 10th-seeded Wozniacki came on a trio of aces, one in the first set, two in the second.That was, in part, a result of the Dane’s iffy play in only her second Grand Slam final — she lost to Kim Clijsters at the 2009 U.S. Open — but more due to Williams’ relentless pursuit of every ball.A few weeks shy of her 33rd birthday, making the American the oldest major champion since Navratilova was 33 at Wimbledon in 1990, Williams simply would not allow a shot to get past her. Wozniacki is the one training for the New York City Marathon, but Williams tired her out by the end.Wozniacki was not exactly an extra in this Williams highlight reel, but pretty close to it. The points were being directed by Williams, whether via serves that reached 120 mph (194 kph), forceful returns that backed Wozniacki into a corner when not producing outright winners, unreachable groundstrokes from all angles or even the occasional volley.