Sharapova into Stuttgart Quarters, Ivanovic Bows out

Women's world number two Maria Sharapova reached the quarter-finals of Stuttgart's WTA tournament on Wednesday while ex-world number one Ana Ivanovic suffered a shock first-round exit.

Sharapova progressed to the last eight of the clay-court tournament after French qualifier Alize Cornet was forced to retire after the first game of the second set with a shoulder injury in the second-round tie.

"You never want a match to finish like that, but we are approaching Roland Garros and, being French, she would want to be fit to be able to play in her home country," said Sharapova.

"I wish her the very best for a fast recovery.

"It is quite a task to adjust to clay, you need matches to find your game.

"The ball bounces differently and you have to be prepared for the longer rallies.

"The only thing that helps is playing matches, that is priceless."

In Friday's last eight tie, Australian Open finalist Sharapova will face either U.S. Open winner Samantha Stosur or Stuttgart's defending champion Julia Goerges, who meet on Thursday.

Sixth-seed Caroline Wozniacki of Denmark is into the second round after opponent Jelena Jankovic was also forced to retire in their opening match.

Wozniacki took the first set 6-3, but Jankovic was forced to retire after 56 minutes with a back problem and the Dane will face Germay's Angelique Kerber on Thursday for a place in the quarterfinals.

Polish fourth-seed Agnieszka Radwanska is also in the last eight following her 6-3, 6-4 second-round victory over Hungary's Greta Arn and she will play either French Open winner Na Li of China or Uzbekistan's Akgul Amanmuradova in the last eight.

Earlier, wild-card Mona Barthel was delighted by her shock first-round win over her former idol Ivanovic in straight set.

The 21-year-old German blasted down 11 aces to out-muscle the Serbian, ranked 15th in the world, for a 7-5, 7-6 (7/4) victory and will now face seventh-seed Marion Bartoli of France in the second round.

"There was something special, because Ana used to be a bit of a role model for me," said Barthel, ranked 35th in the world.

"I was still at school when she won the (2008) French Open and I watched it on television.

"At that time all this was a long, long way off for me."

Ivanovic has struggled for form since she rose to world number one nearly four years ago following victory at Roland Garros.

"It was a tough match, she served really well," said Ivanovic, who was part of the Serbia team which beat Russia 3-2 in Moscow in last weekend's Fed Cup World Group semifinal.

"It's disappointing to lose like this, but I am really tired still from the Fed Cup and she is the sort of player you have to be on top of your game against."

Barthel is part of a batch of promising female tennis players emerging from Germany having won the Hobart WTA tournament in January.

She went on to reach the third round at the Australian Open where she lost to eventual winner Victoria Azarenka, the current world number one.