Fognini was serving at 4-5 to stay in the set when he lost his footing on the clay surface, lost the point and faced a set point.
He then took a swipe at the court with his racket and moaned about the conditions which led to commentator Robbie Koenig saying: “You almost get the feeling he thinks the clay at the back of the court is too slippery.
“That’s what happens when it starts to dry out on a day like today when you’re probably playing at the warmest time.”
On set point, Fognini went long with a backhand to concede the set and he marched disconsolately to his chair.
He sat down and the footage captured him saying: “If you run, you slide everywhere.
“It is impossible to run.
“I’m the only one [inaudible] on the sh***y court. It’s ridiculous.
“I lost six or seven points.”
Koenig then added: “Apologies for the colourful language.
“But you can sense the frustration.”
Before the start of the second set, the court was cleaned and the clay levelled out.
Fognini was then broken early, fell 4-1 down and called for the physio to treat an arm injury.
But he bounced back to break Rublev twice, win the second set and force the match into a deciding set.
Despite Fognini’s complaints, the conditions are set to favour Nadal, who is the 11-time champion.
And world No 5 Dominic Thiem says Nadal is at his toughest in Monte Carlo.
“I saw him yesterday practising again and it looked very good again,” he said. “I think it is very important to believe in it.
“I think in here in Monte Carlo and the Roland Garros it is even tougher because these are his conditions. It’s so tough to hit a winner against him.”