Egyptian winger Mohamed Salah scored with a rare header, helping his side eke a narrow 3-2 win over Sampdoria in a game that was delayed for an hour due to heavy downpour on Sunday.

Roma looked to be heading for a difficult second half at the Stadio Olympico after Sampdoria surged to a 2-1 half-time lead after goals from Fabio Quagliarella and Luis Muriel cancelled out Mohamed Salah's early opener for the hosts.

But Roma coach Luciano Spalletti was given extra time to consider his tactical options when officials delayed the restart by over 30 minutes to render the pitch playable again following a first-half deluge of rain and hailstones.

Totti replaced Diego Perotti and Edin Dzeko came on in place of Stephan El Shaarawy for the start of the second half, and the changes made an immediate impact.

After Kevin Strootman saw his drive palmed away by Emiliano Viviano, Totti set Dzeko up for a shot that forced Viviano to parry for a corner.

Two minutes later, Totti sent Dzeko through in the box and the Bosnian shimmied around Viviano before tapping home from close range to pull the hosts level.

Roma had the momentum, but Salah glanced a header wide from Strootman's deflected delivery and seconds later only the trailing foot of Viviano stopped Dzeko's goalbound shot from crossing the line.

Roma looked all set for a share of the spoils until Dzeko made the most of a Milan Skriniar's challenge in the area.

The referee pointed to the spot and Totti made no mistake, sending Viviano the wrong way to send the fans into raptures.

Roma are now two points behind champions Juventus, who claimed their third successive win with a 3-1 defeat of Sassuolo on Saturday.