Anderson into Winston-Salem semis

Winston-Salem - Second-seeded South African Kevin Anderson powered into the semi-finals of the US Open tune-up tournament at Winston-Salem on Thursday with 6-2, 7-6 (7/1) win over Borna Coric.

Anderson improved to 6-0 in quarter-final matches in 2015, firing 10 aces and never facing a break point in the 82-minute triumph.

He took full advantage of the 18-year-old Croatian's errors in the opening set, when Coric coughed up five double faults and won just three of 11 possible points on his second serve.

In Friday's semi-finals, Anderson will play unseeded Tunisian Malek Jaziri, who upset sixth-seeded Brazilian Thomaz Bellucci 6-3, 6-2.

American Steve Johnson reached the final four without lifting a racquet as Lu Yen-Hsun of Taiwan withdrew from their quarter-final with a back injury sustained in a three-set win over South Korea's Chung Hyeon.

"It happened at the end of the match yesterday," Lu said. "There is some inflammation in a disk, which causes the muscles to tighten up. It's difficult for me to extend my body, especially backwards."

Johnson, bidding to reach his first career final on the ATP Tour, will face French qualifier Pierre-Hugues Herbert, who needed one hour and 57 minutes to overcome Spaniard Pablo Carreno-Busta 4-6, 7-6 (7/5), 6-2.

Carreno-Busta, who had 11 aces and just one double fault, served for the match at 5-4 in the second set, but Herbert hung on to force the third set, breaking the Spaniard twice in the final frame to seal the win.

Quarter finals

Pierre-Hugues Herbert (FRA) bt Pablo Carreno-Busta (ESP) 4-6, 7-6 (7/5), 6-2

Steve Johnson (USA x13) bt Lu Yen-Hsun (TPE) walkover

Malek Jaziri (TUN) bt Thomaz Belluci (BRA x6) 6-3, 6-2

Kevin Anderson (RSA x2) bt Borna Coric (CRO x8) 6-2, 7-6 (7/1)