* Nadal's conqueror pulls out with shoulder problem
* Women's second seed Azarenka withdraws injured
* Tournament over early for five players on Wednesday
LONDON, June 26 (Reuters) - The All England Club's medical rooms were overflowing as the third day of Wimbledon resembled a casualty ward with Rafa Nadal's conqueror Steve Darcis one of five players to withdraw injured before mid-afternoon on Wednesday.
Darcis, who sent shockwaves around the tennis world on Monday with a first-round demolition of Nadal, was in good company with women's second seed Victoria Azarenka unable to take to the Centre Court to face Italy's Flavia Pennetta.
American marathon man John Isner, whose longest-ever tennis match is part of Wimbledon folklore, lasted only two games before his knee buckled against Adrian Mannarino.
Czech veteran Radek Stepanek then quit with a hamstring injury while trailing powerful Pole Jerzy Janowicz 6-2 5-3, meaning the first three men's second round results of the day were decided by walkovers or retirements.
Men's 10th seed Marin Cilic added to the injury list when he withdrew before his second round match against Frenchman Kenny De Schepper.
The 29-year-old Darcis, who had been due to face Pole Lukasz Kubot, said he had injured his right shoulder in the heat of battle against Nadal on Monday.
"It happened against Rafa in the middle of the first set when I fell down," the Belgian told a news conference.
"I started to feel it a little bit. When it was warm, it was okay. I had no pain. After a few games, I was feeling great.
"After the match, a few hours after, I start to feel so much pain, I couldn't sleep the night," he added.
Australian Open champion Azarenka was scheduled to open play on Centre Court but withdrew as fans were taking their seats having failed to recover from the knee injury she sustained when slipping over against Maria Joao Koehler on Monday.
"It's very tough. I couldn't be any more disappointed," Azarenka who won Olympic gold in mixed doubles at Wimbledon last year, told reporters. "Wimbledon is just a tournament I was looking so forward to. I love playing here."
Azarenka, who blamed a slippery No. 1 Court on her fall, said an MRI scan had not revealed a torn ligament and that she had tried to practise before Wednesday's match with Pennetta.
"I tried to stay as optimistic as possible," she said. "I tried to practise today a little bit to see if it was going to get better. It didn't it just got worse."
Organisers quickly had to fill the gap left by Azarenka's withdrawal, switching former world number one Ana Ivanovic to Centre Court for her match against reigning Wimbledon junior champion Eugenie Bouchard of Canada but the 12th-seeded Serb's upgrade did little for her performance as she lost 6-3 6-3.
The biggest irony of the day was 18th seed Isner's painful exit. The American, who beat Frenchman Nicolas Mahut in an 11-hour-five-minute epic in 2010, suddenly grabbed his left knee after a serve in the opening game.
After receiving attention he battled on for a while but threw down his racket at 1-1 and shook hands with Mannarino.
"I didn't feel anything in my first match; didn't feel anything yesterday in practice; didn't feel anything (earlier) today in the warm-up; didn't feel anything in the five-minute warm-up; didn't feel anything in the first two points of the match; and then, bam, felt it."
Defending champion Roger Federer looked a picture of health, however, when he sauntered through the main gates holding the hands of his twin daughters.
The Swiss faces Ukraine's Sergiy Stakhovsky later on Centre Court while British eyes will also be on Court One where home favourite Andy Murray faces Taiwan's Yen-Hsun Lu.
Maria Sharapova, whose route to the final now looks clearer after Azarenka's misfortune, was due on Court Two against Portugal's Michelle Larcher de Brito. (Reporting by Martyn Herman; Editing by Ken Ferris)