Serena Williams, who is 12-3 against Victoria Azarenka but has lost two of their three matches this year, says the Belarussian raises her level in their matches. The two will play in the U.S. Open final for the second straight year on Sunday.

"I definitely feel like when she plays me she plays her best, by far. I have seen her play other players, and when I play her I'm playing a totally different player. Obviously she brings her best game, yeah," said Williams.

Azarenka agreed that the challenge of facing Williams brings out the best in her. "I just really try to play my best tennis, you know. When you play against Serena, you have to play your best because she makes me play my best," said the No. 2 seed. "I think I kind of do the same way to her, you know. I think we kind of raise each other's level all the time and, as I say, take each other to the limit. To go out of that place where you sometimes don't know how far you can go, but you just still go for it."

Both have won a Grand Slam title this year, Azarenka at the Australian Open and Williams at the French Open. The two players, who went three sets in last year's final, agreed that it was important to take the initiative against each other.

"It's just important to really take my chances, because she's a player who doesn't give you anything," said Azarenka. "She's really, really powerful, so it's important to try to find a way to be dictating yourself."

Williams won their meeting on clay in Rome earlier this season but lost both hard-court matches in Doha and Cincinnati. Reflecting on the two losses, Williams said, "Both matches she played really well. I let myself down at opportunities and I didn't take them. If I'm able to get another opportunity I have to take them, because she is always pumped and she does really well."