Rome - Roger Federer's return to the Italian Open was scuppered by rain on Wednesday as officials were forced to cancel the day's play after waiting in vain for more than nine hours for wintery weather to clear.

Federer last appeared at Rome's Foro Italico in the 2016 third round, losing to Dominic Thiem, but he was kept waiting to begin his tournament against Portugal's Joao Sousa thanks to rain and wintery temperatures in what is normally a warm and pleasant period of the year in the Italian capital.

However the dual ATP-WTA clay showpiece will restart at 10:00 (SA time) on Thursday, after a frustrating day that saw starting times regularly delayed until play was officially abandoned at 20:00 (SA time).

The poor conditions also mean last week's winner in Madrid Novak Djokovic and reigning Rome champion Rafael Nadal also have to be crammed into a packed schedule.

Among the women, world number one Naomi Osaka was waiting to start her tournament against Dominika Cibulkova after beating the Slovak in the Madrid first round last week.

Federer, a four-time finalist in Rome, returns to Italy after skipping the clay season for the last two years as he concentrated on his grass game.

The Swiss was originally scheduled to take on Sousa at 11am (0900 GMT) on Wednesday but was among dozens of players kept waiting in crowded locker rooms and lounges, as organisers angered fans with a "no refund" policy after doubling ticket prices for Wednesday to reap the financial benefits of Federer's return to the venue.

They later told disappointed Wednesday ticket holders to come back for free on Thursday, before appearing to open the door for refunds to those who could not make it.

When informed of the decision on Tuesday during a media event, Federer did not seem particularly impressed.

"I heard some fans clearly were not happy about it. That's obviously disappointing to hear," the 20-time Grand Slam champion said.

"I just really hope it doesn't take away the fact I'm really happy to be here."