Wimbledon organisers cited the wet conditions at the start of the tournament as a factor in the apparent slipperiness of the grass at the All England Club this year.
Williams left Centre in tears having hurt her leg early in her clash against Aliaksandra Sasnovich in what could potentially have been her final appearance at Wimbledon.
Mannarino, meanwhile, had limped out of the previous match against Roger Federer having hurt his right knee while two sets to one up.
It is not unusual to see players slipping over during the early days of the tournament, when the grass is at its most lush, and that has been exacerbated by lengthy spells of rain on both Monday and Tuesday.
The All England Club said in a statement: "The preparation of the grass courts has been to exactly the same meticulous standard as in previous years.
"Each grass court is checked by the grand slam supervisors, referee's office and grounds team ahead of play commencing and, on both days of the fortnight, they have been happy with the conditions and cleared the courts for play.
"The weather conditions on the opening two days have been the wettest we have experienced in almost a decade, which has required the roof to be closed on Centre Court and No 1 Court for long periods.
"This is at a time when the grass plant is at its most lush and green, which does result in additional moisture on what is a natural surface. With each match that is played, the courts will continue to firm up.
"The grounds team and Sports Turf Research Institute take hardness readings every morning in order to ensure that the courts have the right level of moisture and are playing consistently.
"Our long-serving grounds team have experienced nearly every combination of weather conditions possible. They keep abreast of and utilise the latest grass-court technologies, prepare for every weather eventuality and react to the current conditions on a daily basis.
"We will continue to monitor these readings and adjust our care plan for the grass appropriately."
The good news for both organisers and players is that the forecast for the rest of this week is much better.
Williams did not do a press conference on Tuesday but issued a statement that read: "I was heartbroken to have to withdraw today after injuring my right leg. My love and gratitude are with the fans and the team who make being on Centre Court so meaningful.
"Feeling the extraordinary warmth and support of the crowd today when I walked on – and off – the court meant the world to me."