Stuttgart - World No 2 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."
Sharapova was leading 6-3, 1-0 when Cornet called it quits.
In Friday's last eight tie, Australian Open finalist Sharapova will face either US Open winner Samantha Stosur or Stuttgart's defending champion Julia Goerges, who meet on Thursday.
Polish fourth-seed Agnieszka Radwanska is also in the quarter-finals following her 6-3, 6-4 second-round victory over Hungary's Greta Arn.
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 semi-final.
"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.
There will be a battle of the former world number ones later when Denmark's Caroline Wozniacki, the sixth-seed here, takes on Serbia's Jelena Jankovic with the winner to face Germany's Angelique Kerber in the second round.
Results from the second day of the WTA tournament on Wednesday (x denotes seeding):
Mona Barthel (GER) bt Ana Ivanovic (SRB) 7-5, 7-6 (7/4)
Akgul Amanmuradova (UZB) bt Dominika Cibulkova (SVK) 6-2, 5-7, 6-3
Caroline Wozniacki (DEN x6) bt Jelena Jankovic 6-3, 1-0 retired
Agnieszka Radwanska (POL x4) bt Greta Arn (HUN) 6-3, 6-4
Maria Sharapova (RUS x2) bt Alize Cornet (FRA) 6-3, 1-0 retired