Maria Sharapova cursed her final-set form in her U.S. Open semifinal defeat to Victoria Azarenka, saying she gave her opponent a free ride on the crucial points.

The Russian world No. 3 went a set and a break up before the top-ranked Belarusian came back to snatch a 3-6, 6-2, 6-4 victory at Flushing Meadows.

"Its frustrating but it's the game of tennis," Sharapova said.

"There were a lot of swings in the match today. ... I didn't do much on her service games, she was winning them pretty easy. On mine, they were quite long, and I wasn't putting too much pressure on her."

"I think I gave her too many free points."

Sharapova, the French Open champion and Olympic silver medalist, reflected on the wider picture too, however, saying she took some consolation in her best U.S. Open performance since her 2006 victory.

It was also the latest episode in Sharapova's increasingly intriguing rivalry with Azarenka, whom she trails 6-4 in career head-to-heads.

"She has the better record against me, but hopefully when I'm done I can change that around," Sharapova said.

Azarenka faces three-time champion Serena Williams in the final.