Justine Henin will open the defence of her WTA Sony Ericsson Championship against Anna Chakvetadze on Tuesday.

The world number one will open the tournament in Madrid against her Russian opponent, a semi-finalist at this year's US Open.

Henin has been drawn in the yellow group, alongside Chakvetadze, Serena Williams and Jelena Jankovic - the latter two begin their campaign on Wednesday.

Williams will be looking to continue her outstanding comeback this season by lifting the title which she last won in 2001.

The American suffered a string of injuries in 2006 which coincided with a slump in form and she finished the year ranked 94th, leading to many experts writing off her chances of competing at the top level again.

Williams announced her return at the start of the year by winning the Australian Open and has been one of the most consistent performers on tour this year.

"I'm delighted and surprised to have made it to the Sony Ericsson Championships," she said.

"When I started the year, I honestly never thought I would be in the position I am in now with a Grand Slam title under my belt and getting closer to playing some great tennis.

"I thought I missed my chance by not playing this summer, but I have been really excited to be playing in Europe the last few weeks and I made it sooner than I thought."

Tuesday's other matches are in the red group.

Maria Sharapova and Daniela Hantuchova - the last two players to qualify for the elie eight-woman field - face off in the day's second match, before the action is concluded with second seed Svetlana Kuznetsova's showdown with Ana Ivanovic.

Ivanovic is happy just to be competing at the US$3million event.

She said: "I'm delighted. At the start of the season I made this my number one goal, so to achieve it is very satisfying.

"As a professional tennis player, I train for the opportunity to play against the top players, and in Madrid we should have all of the world's best players there."

The top two players in each group progress to Saturday's semi-finals.

Henin starts the tournament as a hot favourite to retain her crown. She arrives in the Spanish capital on a 20-match unbeaten streak and with a career-high nine WTA Tour titles to her name this season.

Her last defeat came against Marion Bartoli in the Wimbledon semi-finals back on July 6.