(CNN) -- World No. 1 Victoria Azarenka will face a big test of her new status this weekend as women's tennis moves from singles tournament play to the Fed Cup teams event. The Australian Open champion will lead Belarus into action against the United States for the first time, but despite the stars on show they will be competing in the second tier of the competition. The U.S. team will be led by the Williams sisters Serena and Venus, both former No. 1s and the winners of a combined 20 grand slam singles titles. Serena lost in the last 16 in Melbourne last month, but Venus will return to action in California after a five-month absence after being diagnosed with an autoimmune disorder. Can anyone stop champion Djokovic? "I think just being on a team and just having some adrenaline just gives me even more energy, to be honest," the 31-year-old -- who revealed she was suffering from Sjogren's Syndrome in September -- told reporters. Venus also admitted it was difficult to deal with the restrictions her illness had placed on her attempts to return to the court. She has not played a competitive match since the U.S. Open first round in August, but faced her younger sister in an exhibition match in November. "The difference is acceptance," said Venus, who was part of the U.S. team which lifted the Fed Cup in 1999. "Trying to accept how you feel and limitations. Listening to your body and taking care of yourself. "Instead of trying to run through a wall, just really kind of take a step back and be smart. I think that's kind of what I've learned. "I still have to be reminded to slow down, but hopefully there will be a day when I don't have to be reminded of that." The U.S. team are in the second tier of the tournament for the first time after being relegated from World Group I last year. Serena, a 13-time grand slam winner, is looking forward to teaming up with her sister ahead of their possible pairing at the London 2012 Olympics. "We played on the same team a few times," said Serena, who was also part of the team which defeated Russia in 1999. "We always have a blast and always make the best of everything. "We really enjoy every moment together because we don't sometimes get to spend a lot of time together. It's something that we really enjoy." The main World Group matches see the Czech Republic begin the defense of their title away to Germany, while Australian Open finalist Maria Sharapova leads last season's runners-up Russia against Spain in Moscow. Belgium, who reached the last four in 2011, will be without Melbourne semifinalist Kim Clijsters for the home clash with Serbia, headed by world No. 13 Jelena Jankovic. Italy, beaten by Russia in last year's semis, take on Ukraine on clay in Biella.
World No. 1 Victoria Azarenka will return to the tennis court this weekend .
The Australian Open winner will play for Belarus against the U.S. in the Fed Cup .
Azarenka's first match could be against one of Venus or Serena Williams .
Venus has not played since late August after being diagnosed with an autoimmune disease .
(CNN) -- World No. 1 Victoria Azarenka will face a big test of her new status this weekend as women's tennis moves from singles tournament play to the Fed Cup teams event. The Australian Open champion will lead Belarus into action against the United States for the first time, but despite the stars on show they will be competing in the second tier of the competition. The U.S. team will be led by the Williams sisters Serena and Venus, both former No. 1s and the winners of a combined 20 grand slam singles titles. Serena lost in the last 16 in Melbourne last month, but Venus will return to action in California after a five-month absence after being diagnosed with an autoimmune disorder. Can anyone stop champion Djokovic? "I think just being on a team and just having some adrenaline just gives me even more energy, to be honest," the 31-year-old -- who revealed she was suffering from Sjogren's Syndrome in September -- told reporters. Venus also admitted it was difficult to deal with the restrictions her illness had placed on her attempts to return to the court. She has not played a competitive match since the U.S. Open first round in August, but faced her younger sister in an exhibition match in November. "The difference is acceptance," said Venus, who was part of the U.S. team which lifted the Fed Cup in 1999. "Trying to accept how you feel and limitations. Listening to your body and taking care of yourself. "Instead of trying to run through a wall, just really kind of take a step back and be smart. I think that's kind of what I've learned. "I still have to be reminded to slow down, but hopefully there will be a day when I don't have to be reminded of that." The U.S. team are in the second tier of the tournament for the first time after being relegated from World Group I last year. Serena, a 13-time grand slam winner, is looking forward to teaming up with her sister ahead of their possible pairing at the London 2012 Olympics. "We played on the same team a few times," said Serena, who was also part of the team which defeated Russia in 1999. "We always have a blast and always make the best of everything. "We really enjoy every moment together because we don't sometimes get to spend a lot of time together. It's something that we really enjoy." The main World Group matches see the Czech Republic begin the defense of their title away to Germany, while Australian Open finalist Maria Sharapova leads last season's runners-up Russia against Spain in Moscow. Belgium, who reached the last four in 2011, will be without Melbourne semifinalist Kim Clijsters for the home clash with Serbia, headed by world No. 13 Jelena Jankovic. Italy, beaten by Russia in last year's semis, take on Ukraine on clay in Biella.
(CNN) -- World No. 1 Victoria Azarenka will face a to the Fed Cup teams event. The Australian Open Venus will return to action in California after a five-month absence after being diagnosed with an attempts to return to the court. She has not played a competitive match since the U.S. Open