#USOpen: Serena's show rolls on while Fish bows out
Williams took another step towards her goal with 7-6(5) 6-3 victory over Dutchwoman Kiki Bertens.
NEW YORK - The Serena Williams show continued at the US Open as the world number one moved a step closer to a calendar Grand Slam on Wednesday, while Mardy Fish took a final Flushing Meadows bow as the curtain came down on the American's career.
Defending men's champion Marin Cilic and two-time winner Rafa Nadal also eased into the third round with straight sets win as the temperatures and stakes continue to rise at the year's final grand slam.
Bidding to become just the fourth woman to win all four slams in the same year, Williams took another step towards her goal with an error-strewn 7-6(5) 6-3 victory over Dutchwoman Kiki Bertens.
The 110th-ranked Bertens put up a valiant fight and had Williams, who struggled with her serve firing 10 double faults, on the ropes in the opening set.
However, the 33-year-old American's class shone through in the second set as she broke Bertens three-times to seal her 23rd consecutive US Open victory.
"I never stop. I keep going and give the best effort that I can," Williams said after raising her 2015 match record to 50-2.
After playing his opening match on an outside court, Cilic took his US Open title defence back to Arthur Ashe Stadium and looked right at home, storming into the third round with a 6-2 6-3 7-5 win over Russian qualifier Evgeny Donskoy.
During last year's magical run Cilic was invincible on the main court, sweeping past Tomas Berdych in the quarters, taking out Roger Federer in three sets in the semi-finals and Kei Nishikori in a one-sided final.
"This court is very special for me, brings back special memories," the ninth seeded Cilic said. "It's sort of unreal. I was working all my life to win a grand slam and now I'm in position to defend one."
Two-time champion Nadal got his second round contest off to a sluggish start but the eighth seeded Spaniard was quickly in control, dispatching Diego Schwartzman 7-6(5) 6-3 7-5 as the Argentine saw his record against top 10 opponents drop to 0-6.
After a first round littered with upsets, second round action went largely according to script as Spanish seventh seed David Ferrer beat Serb Filip Krajinovic 7-5 7-5 7-6(4) and Canadian 10th seed Milos Raonic fought off back pain to beat Spain'' Fernando Verdasco 6-2 6-4 6 -7(5) 7-6(1).
It was a great start to another steamy day for the Americans with 19th seed Madison Keys needing just 54 minutes on centre court to race past Czech Tereza Smitkova 6-1 6-2 and reach the third round for the first time in four attempts.
The victory marked another milestone in what has been Keys's best grand slam season, having reached the Australian Open semi-finals, Wimbledon quarters and third round of the French Open.
It was the end of road, however, for Fish, who announced earlier this year that he would retire after playing his 13th US Open.
After an 18-month layoff, Fish, who suffers from a severe anxiety disorder, returned to the ATP Tour in March and went down swinging in his Flushing Meadows farewell, stretching out his final match as long as he could before falling 2-6 6-3 1-6 7-5 6-3 to 18th seeded Feliciano Lopez.
"I have got a lot of great memories; I've got a lot of good wins out here. I have made a lot of really good friendships with almost everyone out here," Fish said.
"I probably would have chosen this one as my last one regardless if I didn't have any issues with my health in the past couple of years, just because this is the biggest one and the most fun and the one that you want to go out on."