WINSTON-SALEM, N.C. - Second-seeded Kevin Anderson of South Africa beat 2014 finalist Jerzy Janowicz of Poland 7-6 (2), 6-4 on Wednesday to advance to the quarterfinals in the Winston-Salem Open.

In a battle of big hitters — both players are 6-foot-8 — the 15th-ranked Anderson served 17 aces and took advantage of a service break in the second set to improve to 3-0 against the 16th-seeded Janowicz.

"I was really pleased with today's performance," Anderson said. "It was an improvement from yesterday. I really served well today, and that was my big goal. I really took care of my own serve games, especially when you're playing a big server like Jerzy, that's one of the most important aspects.

"I also did a good job of staying patient on the returns. I didn't necessarily feel I returned my best, but when it counted, I definitely made some returns."

Janowicz, who beat defending champion Lukas Rosol in the second round Tuesday, was clearly frustrated in the second set. He was twice called for foot faults, and was given a code violation for hitting a ball out of the stadium after the service break.

"The first set was a good fight for both players," Janowicz said. "You never know how it's going to be in a tiebreak, but I lost it. But the second set was completely destroyed by the linesmen. They called a foot fault after my ace when it was 30-all, and that destroyed my match right there.

"Being broken is nothing really special, but being broken because of the linesmen, this is painful. It's quite annoying when its 30-all in an important game, and they call a foot fault."

Anderson will face 18-year-old Borna Coric of Croatia on Thursday. The eighth-seeded Coric beat Argentina's Diego Schwartzman 6-2, 6-1.

Also, sixth-seeded Thomaz Bellucci of Brazil beat 11th-seedeed Jiri Vesely of the Czech Republic 6-1, 6-7 (7), 6-4; Taiwan's Yen-Hsun Lu topped South Korea's Hyeon Chung 7-6 (1), 1-6, 7-5; and Tunisia's Malek Jaziri beat 15th-seeded Teymuraz Gabashvili of Russia 7-5, 6-4.

France's Pierre-Hugues Herbert beat Britain's Aljaz Bedene 6-3, 6-0, and Spain's Pablo Carreno Busta topped Italy's Simone Bolelli 6-4, 4-6, 6-1.

Later Wednesday at Wake Forest Tennis Center, France's Jo-Wilfried Tsonga, ranked 19th in the world and the No. 3 seed, faced 13th-seeded Steve Johnson, the only American remaining in the tournament.

In the other quarterfinals, the Tsonga-Johnson winner will play Lu; Bellucci will face Jaziri; and Herbert will meet Carreno Busta.