Gervinho popped up with a late winner to spare Roma's blushes when it looked like Napoli had pegged them back. The Giallorossi were in cruise control after first half goals from Gervinho and Kevin Strootman put them firmly in the driving side. Napoli made a spirited second half comeback and wiped out the deficit thanks to strikes from Gonzalo Higuain and substitute Dries Mertens, before the Ivorian striker's late show. The second leg will be played in Naples next Wednesday.
Rafa Benitez was in recovery mode after seeing his makeshift Napoli side humbled by a 3-0 defeat at Atalanta. There was no sign of his rotation policy here, with all of the stars restored to the starting lineup. There had been a constant downpour in the Eternal city, but the Stadio Olimpico pitch had dried out somewhat since the weekend's abandoned game, so this match went ahead.
However, the Giallorossi shocked their visitors when they took the lead with their first attack on 13 minutes. Francesco Totti showed great vision to deliver a perfectly weighted pass to play Gervinho in behind the defence. The forward cleverly dinked the ball over an advancing Pepe Reina, then tapped into an empty net.
Totti stung Reina's palms after being given licence to run at goal, while Gokhan Inler and Insigne both blazed efforts over the bar at the other end. Faouzi Ghoulam made an impromptu Napoli debut when Anthony Reveillere was forced off with a foot injury on 25 minutes.
Jose Callejon failed to tap in Higuain's cross turned shot at the far post. Napoli were made to pay for that failure when Roma scored a spectacular second just past the half hour mark. Strootman advanced with the ball and let rip with a 25 yard rocket, which flew past Reina into the top corner.
The rain came back down. Radja Nainggolan tried to replicate Strootman's effort, but his shot was always rising. The Belgian picked up a costly yellow card to rule him out of next week's return leg. Morgan De Sanctis denied Insigne, as the Neapolitan bent a shot comfortably into his gloves.
Two minutes before half time, Gervinho burst clear again. Totti's failure to keep up ruled out a square pass, so the forward cut the ball back for Maicon. Raul Albiol did enough to force the Brazilian to shoot into the side netting.
A minute before the break, Christian Maggio nicked the ball from Vassilis Torosidis in the box. The Romanian did well to get back and lean in to dispossess the full back before he could pull the trigger.
For all of Roma's first half dominance, De Sanctis gifted his former team with a crucial away goal 60 seconds after the restart. Higuain drifted away from his marker out wide and his cross was deflected goalwards by Mehdi Benatia, resulting in the ball slipping through De Sanctis' hands and into the net.
Adem Ljajic tried to restore Roma's two goal cushion. The Serbian pounced on a Maggio error and forced Reina to turn a shot around the post. Reina could only watch as Ljajic went on another run shortly after and dragged his effort wide of the post.
Ghoulam failed to test De Sanctis from a weak free kick, before Ljajic wasted a third chance. The forward opted to go it alone in the box, and his attempt to beat Reina at his near post finished in the side netting.
Garcia introduced Miralem Pjanic - who netted both goals in Roma's 2-0 victory over Napoli when the two sides last met in Serie A back in October.
Reina showed great reactions to catch a Torosidis shot, which deflected off the head of Jorginho and looped towards goal. Totti failed to reach Gervinho's pass across the box, in what was to be his final contribution of the night. The veteran made way for Mattia Destro.
Napoli amazingly levelled the tie on 70 minutes. Higuain went down under a foul from Benatia, but the referee played the advantage when he saw the loose ball fall kindly to Mertens. The Belgian - who had only been on the pitch less than five minutes created an opening for himself and lifted the ball over the onrushing De Sanctis.
Gervinho ensured he had the final word, when the game produced yet another twist two minutes from time. Alessandro Florenzi exchanged passes with Destro, then threaded through for the ex-Arsenal man to take a touch in the area and smash a low shot past a hapless Reina.
AS Roma: De Sanctis; Maicon, Benatia, Castan, Torosidis; Nainggolan, (Pjanic 60) De Rossi, Strootman; Ljajic, (Florenzi 72) Totti, (Destro 65) Gervinho
Napoli: Reina; Maggio, Fernandez, Albiol, Reveillere; (Ghoulan 25) Inler, Jorginho; Insigne, Hamsik, (Mertens 66) Callejon; Higuain (Behrami 85)
Goals: Gervinho 13, 88 (R) Strootman 32 (R) Higuain 47 (N) Mertens 70 (N)