US Open - Sharapova and Azarenka hiding in Serena's shadow
They have five Grand Slam titles between them, one each this year and one of them is the world No 1.
The American is everyone's favourite and while world number one Azarenka was reluctant to admit to playing second fiddle, Sharapova was more open about the predicament facing the rest of the field.
"Of course she's the favourite because she won those two big events back to back," said Sharapova, who was beaten by Serena in the final of the Olympics.
"She gained a tremendous amount of confidence at Wimbledon, getting through a few tough three-set matches and then when she got to the Olympics, she just improved."
However, neither Sharapova nor Azarenka are willing to throw in the towel just yet.
"Everybody is still in the draw here," said Sharapova, who completed a career Grand Slam when she won the French Open in June. "It starts from the first round on, and that's why everybody is here."
Sharapova has not played since winning silver at the Olympics but said she felt strong going into the event she won in 2006.
"I feel really good," she said. "I was supposed to play in Montreal but I got a stomach bug and just decided to give it a rest.
"I think it was a sign my body just needed to slow down. It was a lot of travel, a lot of playing. So I decided to shut it down until here, because we still have a lot to play towards the end of the year."
Azarenka, who lost the world number one ranking to Sharapova in Paris but regained it at Wimbledon, said she was focused solely on herself.
"I think it's your guys' job to pick the favourite and to look at the draw," Azarenka said. "I never look at the draw.
"When I go into the tournament I'm trying to think just about my opponent on that particular day."
Azarenka won the bronze medal at the Olympics and said she had needed the rest to recover from the emotional and physical exertion.
"I was absolutely drained because I went through so much in a few days, something that I have never been through before," she said.
"It took so much energy out. I'm glad I had an opportunity to have a little bit of break and to make sure that, you know, I can prepare for the US Open as best as I can. I am feeling good."