Caroline Wozniacki and Maria Sharapova are both wary of the challenge the Williams sisters will pose at Wimbledon, when the tournament gets underway on Monday.

25732 - Wozniacki wary of Williams threat

The two Americans are returning to competitive action after long layoffs through injury, with both only showing fleeting glimpses of their quality at the AEGON International in Eastbourne this week.

Despite their lack of recent tournament action Serena and Venus have been seeded seventh and 23rd respectively for the grand slam, and No. 1 Wozniacki is relieved as that means she will not have to face either of them until the latter stages.

"Obviously no one wants to play them. They have the experience and play really well, especially on grass," Wozniacki said. "It's good that they got a higher seed than their rankings because no one wants to play them in the early rounds.

"We have to see how they do but grass is a little bit of a different surface. Here it's important to serve and return well.

"We all know that the game of the girls is perfectly suited for the grass.

"I read somewhere that in the last 11 years a Williams has won here nine times. It just says something about what great champions they are, but also how well they're playing on grass."

Sharapova beat Serena Williams to win at the All England Club in 2004, but she believes the duo are still favourites at SW19.

"They've been champions here for many years," she said. "They're obviously the ones to beat on grass. They've been out for a while so it's definitely great to have them back."

The Russian fancies her chances of clinching a second victory, however, after a solid performance at the French Open - where she reached the semi-finals.

She added: "I'm playing a lot better. I played a lot of matches on clay, which I really wanted to do. One of the reasons I love the transition is because I feel like you learn so much about the game when you're on the clay courts.

"This is one of the best parts of the year for me. It's one of the toughest transitions from clay to grass, but for me it's a lot of fun."