By Richard Pagliaro | Wednesday, August 19, 2015

Serena Williams bounced up and down behind the baseline like a boxer raring to come out of the corner.

The world No. 1 was fighting on multiple fronts at times today battling tricky Tsvetana Pironkova, thick, muggy air and gnawing frustration when her shots missed the mark.

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Ultimately, Williams kept her feet moving, landed some powerful combinations and timely strikes. Serena slashed 15 aces launching her Cincinnati title defense with a 7-5, 6-3 conquest that spanned exactly 90 minutes and concluded right before the rains came again.

Bouncing back from her sometime erratic three-set loss to 18-year-old Belinda Bencic in the Toronto semifinals Saturday night, Williams showed signs of frustration at times, but elevated both her aggression and accuracy at critical moments.

"I love playing obviously and I'm really intense. I'm a little bit of a perfectionist," Williams said immediately afterward. "I just want to do the best I can, especially playing in front of a great crowd, you want to play really well."

Clearly, the defending U.S. Open champion is intent on sharpening her strikes and footwork before she arrives in New York continuing her quest to complete the calendar Grand Slam and equal Steffi Graf by collecting her 22nd Grand Slam title.

Early on today, it almost appeared at times Williams' feet were in Ohio, but her mind seemed to be on New York. She sometimes bounced up and down trying to remind herself to keep her feet moving. Serena needed no reminders of how dangerous Tsvetana can be: in two of their three meetings the Bulgarian pushed the American to three sets. Pironkova has beaten Serena's older sister Venus in three of four meeting, including successive Wimbledon wins in 2010 and 2011.

Contesting her first second-round match in Cincinnati, Pironkova was patient and persistent. Beneath a pale purple Nike visor, Pironkova stood up to Williams' shots and hit her targets on serve for much of the first set. Despite tape wrapping her left thigh, the 42nd-ranked Bulgarian ran well and changed direction effectively in the opening set trying to keep the top seed off balance.

Williams' second serve was vulnerable in her loss to Bencic and Pironkova took her cracks at it today, winning 12 of 18 points played on her opponent's second serve and earning three break points in the opening set. Williams saved them all.

In the 12th game, Williams whipped a forehand down the line, converting her first break point to snatch a tight first set.

Trying to take charge in the second set, Williams was doing the right thing moving forward, but hurt her own cause guiding some of her approaches without full commitment rather than snapping through those shots as she typically does. She won half of her net approaches (five of 10) in the match.

Indecision was evident in the fourth game when Williams created the short ball, but rather than swoop in to take the swing volley out of the air, she let the ball bounce knocking an awkward forehand into top of tape as Pironkova held for 2-2.

At that point, the 21-time Grand Slam champion began moving to the ball quickly and completing her swings with more conviction.

"I always just try to play my game and be consistent and just stay focused," Williams said. "(I did) nothing really tactically particularly. I just wanted to stay focused and play the best I could."

Rousing herself with an inside-out forehand and a shout, Williams worked one of her best combinations, dragging her opponent wide with the slider serve, before belting a backhand crosscourt, holding at 15 for 3-2.

The forehand return and serve were the knockout shots today. Reading her opponent's slice serve, Williams jolted a forehand return winner down the line leaned into a backhand winner crosscourt for break point in the eight game. Unloading on another forehand winner down the line, she broke for 5-3 with a shout. She finished with 28 more winners (38 to 10) than Pironkova.

Slashing a 115 mph ace down the middle for triple match point, Williams thumped her 15th ace to seal the 90-minute win.

Williams will play Karin Knapp for a place in the quarterfinals in the first meeting between the pair. The hard-hitting Italian defeated Daria Gavrilova, 6-4, 6-1.