Francesco Totti became Serie A's joint second-highest overall scorer when he converted a penalty in AS Roma's 3-1 win over Genoa and Pescara's Cristiano Bergodi became the 12th coaching victim of the season after a home defeat by Udinese.
Inter, without striker Antonio Cassano following a dressing-room row, trailed 2-0 after 20 minutes but in one of the season's most dramatic fightbacks, half-time substitute Rodrigo Palacio scored twice, including a stoppage-time winner.
Struggling Palermo managed a fortuitous 0-0 draw at Torino as Gasperini bizarrely began his second stint as their coach almost exactly a month after being fired.
The Sicilians, who began the weekend bottom of the table, moved level on 21 points at the bottom of the table with Siena and Pescara, who both lost.
Fiorentina beat Chievo 2-1 and Argentine 20-year-old Mauro Icardi gave Sampdoria a 1-0 win over Parma.
Inter's win took them level on 47 points with Lazio in fourth place, one behind arch-rivals AC Milan who are in the Champions League qualifying round spot. Juventus lead with 59 points followed by Napoli on 53.
One-club man Totti, 36, opened the scoring with a 16th- minute penalty, drawing him level on 225 goals with Sweden's Gunnar Nordahl who played for AC Milan and AS Roma in the 1940s and 1950s. He is still way behind Silvio Piola's mark of 274.
Although Marco Boriello replied with another penalty three minutes before half-time for Genoa, second-half goals from Alessio Romagnoli and Simone Perrotta sealed Roma's win.
POOR DEFENDING
Catania and Inter started their match with 15 South Americans between them and the Sicilians, whose campaign has surpassed expectations, got off to a flying start with help from the disorganised visitors.
Inter defender Juan Jesus made a hash of a clearance and Argentine forward Gonzalo Bergessio took advantage to drill the ball home after seven minutes.
There was more poor defending from the visitors as Giovanni Marchese, the game's only non-Argentine scorer, headed the second 12 minutes later when he was picked out by Francesco Lodi's floated free-kick.
The game changed dramatically after Palacio entered the fray at half-time.
Seven minutes after coming on, he sent a cross over from the right and Ricky Alvarez stooped to head Inter's first, then Palacio scored himself in the 70th minute, also from a header following Alvaro Pereira's cross.
Esteban Cambiasso missed a chance to win the game for Inter when his volley flashed wide in the dying minutes but Palacio made no mistake in the second minute of stoppage time, scoring from close range after Cambiasso crossed from the byline.
Palermo lived dangerously throughout the match at Torino as Rolando Bianchi hit the post for the hosts in the first half and Giuseppe Vives fired over the bar from close range. The hosts missed a host of other chances.
