Coco Vandeweghe has slammed the behaviour of Maria Sharapova during their Wimbledon quarter-final this afternoon.

Sharapova progressed into the last four at SW19 for the first time since 2011 courtesy of a 6-3 (3)6-7 6-2 victory over her American opponent, but found herself accused of unsporting behaviour after the match.

Vandeweghe claims that the Russian was moving in her line of sight during her serving motion, and suggested that the umpire was "too scared" to act upon her on-court complaints about the problem.

"She was moving around in the middle of my motion on my second serve. That's why I spoke to the umpire. I felt from her moving around in between my serving motion was not sportsmanlike in my opinion," Vandeweghe told reporters.

"I try to play as fair as I can. When I felt like it wasn't being reciprocated, that's when I spoke with the umpire for her to deal with it.

"[The umpire] said she didn't believe she was doing it during the motion: I strongly disagreed. Towards the later end of the second set, I said if she has a problem speaking to Maria, if she's too scared to do it, I had no problem speaking to her."

Sharapova will face world number one Serena Williams in the semi-finals.