Serena Williams: 'Venus Williams is playing great at the US Open'

World number one Serena Williams has talked up the form of her sister Venus Williams ahead of their looming quarter-final clash at the US Open.

The experienced sisters have been in ominous form so far in New York, and Serena has moved to compliment her older sister as they prepare to face each other in the last eight of the showpiece next week.

"She's playing great," said Serena, according to sportinglife.com

"I barely had time to get ready for my match because she played so fast. I was hoping she'd lose a few games for the first time.

"I have to play like I did today or better. A Williams will be in the semis at least so that's good."

The world number one is looking to clinch her 22nd Grand Slam title at Flushing Meadows.