Roger Federer was due to open play on Court Centrale against Joao Sousa at 10am BST.
But rain from early in the morning has not subsided and meant that by 1.30pm, play still had not started.
In light of the congestion caused by the rain, officials have attempted to spread the matches around in a bid to get as many matches as possible played.
The matches on Centrale remain unchanged but won’t start before 2pm.
It means Novak Djokovic, who is not due on Centrale until after 6.30pm, faces a battle to get his match against Denis Shapovalov played.
On Grandstand, Dominic Thiem’s clash Fernando Verdasco has been swapped with Amanda Anisimova vs Kiki Bertens while David Goffin vs Juan Martin del Potro, which was due to be the last match has been moved to Pietrangeli.
Taylor Fritz vs Kei Nishikori has been moved from Pietrangeli to Court while Mihaela Buzarnescu vs Julia Goerges is now on Court 6.
Seven doubles matches have been cancelled but Bob and Mike Bryan vs Karen Khachanov and Marc Lopez remains on the schedule.
With the continued delays, controversy is brewing over whether fans will receive a refund if there is no play.
The Italian Open policy states that if no matches start, fans would be offered tickets for another day or next year’s event but if just one point is played, there will be no refund.
That will frustrate fans who bought tickets for Federer’s matches and had to pay double after organisers increased the price following confirmation of his appearance in Rome.
But Amazon Prime pundit Mark Petchey feels the Masters 1000 event had every right to cash in on Federer and increase the price.
“I think it is very acceptable to be honest,” Petchey told Amazon Prime.
“I don’t really have a big problem with it. Roger said it was a little disappointing.
“But what it does say from a tournament perspective is if you buy your tickets before you know a marquee player is going to play then you’re going to get the benefit.
“I think going forward for the tournament it has been a very smart and commercial move.
“It’s nothing that we haven’t seen before. This is a commercial entity. This is not a charity and I don’t have a problem with it at all.”