article: Stars of women's tennis put on their glad rags to attend the Porsche Grand Prix Tennis opening ceremony in Stuttgart on Monday. Defending champion Maria Sharapova was joined by players including Ana Ivanovic, Caroline Wozniacki, Sabine Lisicki, and Angelique Kerber ahead of their opening matches at the clay court tournament. The ladies were dressed glamorously as they posed for pictures at the Porsche Arena accompanied by a group of school children. Ana Ivanovic (L-R), Sabine Lisicki, Angelique Kerber, Caroline Wozniacki and Maria Sharapova strike a pose . Ivanovic speaks to Wozniacki (right) during the opening ceremony of the Porsche Grand Prix Tennis event . The women's tennis stars wave to the crowd ahead of their games at the clay court tournament in Stuttgart . World No 1 Serena Williams was the the highest profile absentee, admitting she was not ready for the clay court season after struggling to beat Sara Errani as the USA crashed out of the Fed Cup to Italy last week. 'I'm totally not as ready for the claycourt season as I thought I was. Now I'm in the mindset of, 'You know what, I'm not on hard court.' I'm playing like I'm on hard court and I'm not,' said Williams afterwards. 'So I have to play and be ready to hit a thousand shots if necessary.' Meanwhile, the Stuttgart event could decide who is ranked second in the world with Simona Halep close to overtaking Sharapova in the WTA list. The Russian needs to reach the semi finals at least to retain her current ranking while Halep will move up a spot if she can better the No 1 seed's progress. Ivanovic is escorted by a young mascot onto the court at the Porsche Arena . Sharapova (right) is top seed at the event she has won for the last three consecutive years . Local favourite Lisicki waves to the crowd as she takes the court with a young Germany fan . Wozniacki speaks to the media before getting her singles campaign underway . However, Sharapova, who has won the Stuttgart tournament for the last three years, is confident of hold on to her ranking. 'Despite everything, it's always a nice feeling to come back to an event where you've had a really good record. where you've had some great matches, great memories,' Sharapova told the WTA website. 'Some of the best matches of my career have been played on that court. But every year you come back to a tournament you start from the very beginning, and that's what I'll be doing this year to try and defend my title.' Veterans Andre Agassi (left) and Thomas Muster staged an exhibition match before the tournament started .
highlights: Women's tennis stars attended opening ceremony of Porsche Grand Prix .
  Maria Sharapova, Caroline Wozniacki, Sabine Lisicki, Angelique Kerber and Ana Ivanovic were among the players on show .
  With Serena Williams missing, Simona Halep could overtake three times winner Sharapova as world No 2 .
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