Sharapova laments inconsistency after US Open exit

After her loss at the US Open, Maria Sharapova said she was still searching for consistency.

Russian Maria Sharapova

Maria Sharapova was left frustrated by her inconsistency after making a fourth-round exit at the US Open on Monday.

The Russian's perfect record in night matches on Arthur Ashe Stadium was ended in a surprise 6-4 6-3 defeat to Carla Suarez Navarro.

Since returning from her drugs ban last year, Sharapova has made just one quarter-final in five grand slams.

Asked what the most disappointing aspect of her game was, the five-time major champion said: "I think not being able to consistently put up the level from one match to another, stringing obviously in a span of hopefully a total of seven matches during a grand slam.

"It's just a little too up and down."

Suarez Navarro celebrated her 30th birthday in style, the straight-sets win ending Sharapova's streak of 22 consecutive victories in night matches on Arthur Ashe Stadium.

The seven-time grand slam quarter-finalist, who faces Madison Keys in the last eight, said she was aware of Sharapova's record.

"I know that she never lost on night session because last night I saw her match a little bit, and they put it on the TV. But, well, nothing changes for me about these things," Suarez Navarro said.

"But Maria, she's a really good player. I mean, she's one of the best. Well, I'm happy to beat her."