London: Serena Williams was so shocked by the defeats of Roger Federer and Maria Sharapova and the injury carnage of black Wednesday at Wimbledon that she feared she would be next on the hit-list.
Defending champion Williams saw title rival Sharapova, the third seed, beaten by Portuguese qualifier Michelle Larcher De Brito, just hours after world number two Victoria Azarenka withdrew with a knee injury.
Azarenka was one of seven players to pull out of the tournament through injury on Wednesday against a background of criticism over the state of the All England Club courts.
"Seeing all the falls, seeing all the slips, I definitely was a lot more aware going out there today, a little more on my toes," said Williams who extended her winning streak to 33 with a 6-3, 6-2 win over French teenager Caroline Garcia.
Her match was on the same Court One where Azarenka hurt her knee in a fall in her first round win on Monday and which prompted her withdrawal.
It was also the same arena where world number 135 Steve Darcis fell and injured his shoulder in his stunning win over Rafael Nadal.
Darcis, too, was forced to withdraw as a result.
"For me the court played okay. But I went in there with a mind of frame to be careful and be ready," added Williams.
"The first thing I do is I'm like, Okay, Serena, stay focused. This happened before. Definitely want to stay focused and stay serious."
Williams, the holder of 16 Grand Slam titles, admitted she was shocked to see Federer slip to his worst defeat at a major in a decade when he was beaten in the second round by Sergiy Stakhovsky, the world number 116.
"I think Stakhovsky played really well. I think he played excellent. I thought Roger played well. Obviously Roger can play a lot better, which is something he can always take with him," said Williams.
"So it's just weird, that's all."
Australia's Bernard Tomic believes the courts are more slippery than usual and said he had fallen a number of times in his first round win over Sam Querrey of the United States on Tuesday.
"We're moving in the centre of the court. When we get dragged wide, I think the court is very slippery because it's still grain. People don't realise that," said Tomic, who is safely into the third round after beating US veteran James Blake.
"When we get taken out wide, the grass is green, very slippery. I think maybe that's due to players falling down.
"I fell twice already, and that was on the green grass when I've been taken out wide."
Meanwhile, France's Michael Llodra retired from his second round match against Italian 23rd seed Andreas Seppi on Thursday, taking the total of pullouts to 12 at the tournament.
Llodra's pull-out, believed to be through illness rather than injury, followed the record of seven on Wednesday.
France's Paul-Henri Mathieu joined the casualty list later on Thursday when quit against Feliciano Lopez while trailing 6-3, 5-1.
The nine second round retirements/walkovers set a new record for the most in a single round at Wimbledon in the Open era and equalled the all-time record for a single round.
According to the International Tennis Federation (ITF) the previous most retirements/walkovers in a single round at any Slam in the Open era was nine in the first round at the 2011 US Open.
The most in total at Wimbledon in the Open era is 13 in 2008.
Wimbledon head groundsman Neil Stubley insisted that the All England Club courts have been prepared the same way this year as they have always been.
"They are the same height, the same soils, the same rolling regime. The firmness of the courts is where it should be at this stage of the tournament," Stubley told the BBC.
"I don't know why the players are slipping more. We have prepared the courts the same as always."
Former Wimbledon champion John McEnroe believes the problems have been caused by a combination of footwear and physique.
"Tennis shoes seem to be more flexible, payers see to be able to slide even on hard courts. Maybe they should have different shoes for grass where it's not so easy to slide," said the American.
"Players are also getting taller. They are further from the ground, maybe the should take smaller steps."