Murray reached the semi-finals in Monte Carlo last time out
Britain's Andy Murray was denied by the elements as his second-round tie in the Rome Masters was postponed on Tuesday.
The world number four and fourth seed had a bye into round two and was due to face Juan Monaco of Argentina.
But rain prevented play until late afternoon and organisers moved the match to Wednesday at 1200 BST.
Defending champion Novak Djokovic did not start against Albert Montanes until after 10.30pm and it was gone midnight when he sealed a 7-6 (7-5) 6-0 victory.
Paul-Henri Mathieu led 11th seed David Ferrer 6-3 0-1, 30-30, when play was suspended because of darkness, while Florent Serra was 6-5, 15-0, up on 16th seed Radek Stepanek.
earlier beat Marat Safin 2-6 7-6 (7-5) 6-2, and Italy's Andreas Seppi
was out on court until late in the evening to beat Sam Querrey 3-6 6-4 6-3.
His prize is a second-round meeting with world number one Rafael Nadal.
Murray and Monaco have met once before, with the Briton winning 4-6 6-3 6-2 on his way to victory in Miami last Month, and the Rome draw could have been kinder for the Scot.
"It's very difficult," Murray told BBC Radio 5 Live. "He had a bad illness last year and before that was ranked inside the top 20, and clay is his best surface so I'm going to have to play very, very well to beat him.
"He came through qualifying, he won his first round very easily and he's going to be confident so I'm going to give it my best shot."