WIMBLEDON — And then there was one.

One American is left in contention at Wimbledon.

On a day both Williams sisters lost in the women’s bracket, men’s 10th seed Mardy Fish — who has never before reached the quarterfinals at the All England Club — was the lone Yank still standing

yesterday after his 7-6 (5),

6-4, 6-4 victory over 2010

runner-up Tomas Berdych

of the Czech Republic.

Fish, a 29-year-old Minnesota native, has never been to the semifinals of a Grand Slam tournament — and he faces a steep challenge if he wants to make Wimbledon his first trip to that level.

His quarterfinal foe is top seed and defending champion Rafael Nadal, who survived a foot injury and the hard-hitting Argentine Juan Martin Del Potro. Nadal won 7-6 (6), 3-6, 7-6 (4), 6-4.

“Last [American standing] — not what you set out

to do,” said Fish, who is 0-5 against Nadal.

Fish was a quarterfinalist at the 2007 Australian Open and 2008 U.S. Open.

Yesterday against Berdych, he hit 23 aces and saved both break points he faced. He finished with 42 winners and

only 12 unforced errors. He

won the point on 20 of 25 trips to the net.

The sixth-seeded Berdych had not lost a set through his first three matches.