* Roma end run of four successive draws
* Juve top by three points
* Inter and Parma draw 3-3 (adds Inter v Parma, writes through)
Dec 8 (Reuters) - Serie A title challengers AS Roma ended a run of four successive draws with an enthralling 2-1 win over Fiorentina on Sunday, helped by an inspirational display from Gervinho who set up both goals.
Mattia Destro scored the winner for Roma, only eight minutes after coming on for his first appearance of the season after an injury nightmare, as they remained unbeaten in second place and three points behind leaders Juventus.
Inter Milan and Parma produced shocking defending as they shared six goals at San Siro, the second 3-3 draw of the weekend after Napoli's equally eventful match against Udinese on Saturday.
Roma's neighbours Lazio continued their downward slide by losing 1-0 at Torino, their sixth league game without a win, and Cagliari and Verona each produced dramatic turnarounds to win 2-1 at home.
Marco Sau scored two late goals to give Cagliari a highly controversial 2-1 win over 10-man Genoa who took an early lead through Alberto Gilardino and were furious about Thomas Manfredini's red card two minutes before halftime.
Manfredini was clearly manhandled by Daniele Conti at a corner but both were booked and the Genoa player was dismissed for a second yellow card.
Verona also scored twice in the last 10 minutes to beat Atalanta 2-1, Jorginho scoring the winner with a penalty.
Sampdoria gave coach Sinisa Mihajlovic his first league win since taking over, beating bottom-of-the-table Catania 2-0 thanks to second-half goals from Eder and Manolo Gabbiadini and climbing to joint 16th with 14 points.
Serie A is already threatening to turn into a two-horse race with five points separating Roma (37) and third-placed Napoli, and Inter another four points behind in fourth. Juventus have 40 points after their 2-0 win at Bologna on Friday.
Gervinho has enjoyed a new lease of life since his move from Arsenal in the close season and tormented Fiorentina's defence as Roma recaptured the form which helped them win their first 10 games.
The mere presence of talismanic forward Francesco Totti on the substitutes' bench, after more than a month out through injury, also appeared to inspire Rudi Garcia's side, even though the 37-year-old did not play.
Only a needless sending-off for Miralem Pjanic, who received a second yellow card for fouling David Pizarro inside the opposition's half in the 87th minute, spoiled Roma's day.
Maicon put Roma ahead with his first goal for the club, the Brazilian bundling the ball home in the seventh minute after Gervinho pulled the ball back.
"Gervinho is fast, devastating, has quality and tends to make the right decisions," said Fiorentina coach Vincenzo Montella.
Fiorentina levelled on 29 minutes when Peru midfielder Juan Vargas rifled home from a Nenad Tomovic pass.
Both sides created openings early in the second half before Roma grabbed the game by the scruff of the neck.
Gervinho had a shot blocked by Neto and Kevin Strootman hit the Fiorentina post as the pressure mounted, the winner finally arriving when Gervinho pulled the ball back from the byline and Destro fired home.
The overjoyed Destro, sidelined for 10 months with a knee injury, was mobbed by his team mates and booked for taking his shirt off in the celebrations.
"It was a fascinating game with two teams playing great football," said Montella. "I think either side could've won considering the performances."
The fun started early at San Siro when Nicola Sansone gave Parma an 11th-minute lead.
Rodrigo Palacio equalised in the 44th minute, only for Inter goalkeeper Samir Handanovic to let a harmless shot slip through his hands and gift Marco Parolo another Parma goal in stoppage-time.
Palacio headed in a Ricardo Alvarez cross to equalise again in the 54th minute and Fredy Guarin put Inter ahead with a deflected shot two minutes later, but Sansone levelled for Parma just before the hour.
(Reporting By Brian Homewood; Editing by Ed Osmond)