REGGIO CALABRIA - Ivan Ramiro Cordoba drove in an injury-time winner as Inter saw off a determined Reggina side at the Stadio Granillo.
The Nerazzurri were two goals to the good inside 24 minutes with efforts from Maicon and Patrick Vieira, but Nevio Orlandi's side reduced the arrears through Francesco Cozza before the break and then grabbed an equaliser early in the second half through Franco Brienza.
With time running out Colombian defender Cordoba scored as Inter reclaimed the Serie A top ahead of Sunday's batch of fixtures.
Inter played a 4-2-4 lineup in Reggio Calabria, with Mourinho naming Quaresma, Ibrahimovic, Balotelli and Mancini in attack. Behind them were Zanetti and Vieira, with Maicon, Cordoba, Chivu and Maxwell protecting Julio Cesar's goal.
The Brazilian keeper was called into action early on, making a save from Vigiani's low shot.
Inter's first chance fell to Quaresma who fired on to the upright after Reggina failed to clear Balotelli's cross.
Maicon gave Inter the lead in the 9th minute, crashing into the roof of the net after meeting Ibrahimovic's pinpoint through pass.
Quaresma set up Inter's second in the 24th, playing in Vieira who drove low under Campagnolo for his first goal of the season.
Reggina rallied and Cozza cut the lead in half with a splendid effort from the edge of the box on 34 minutes, becoming the first player to pierce the Nerazzurri net in over four games.
The Amaranto went close to a quick second with Brienza flashing his low free kick just wide of Julio Cesar's right-hand post.
Ibrahimovic had a goal disallowed for offside and Julio Cesar tipped round Cozza's shot as both team produced chances before the break.
Reggina squared up the game eight minutes after the restart when Brienza drilled past Julio Cesar with a well taken shot on the turn.
The equaliser prompted Mourinho to shuffle his pack. On came Crespo for Mancini and the Nerazzurri created at least a dozen chances but found Campagnolo on top form. The Reggina keeper made a string of saves from Crespo, Balotelli and Ibrahimovic, who headed wide on three occasions.
The hosts had chances of their own and substitute Di Gennaro almost found the top left corner with a brilliant curling cross, before Julio Cesar was forced into a one-handed save from Carmona.
Just when it looked like Reggina had done enough for a draw, Cordoba popped up in the area and stabbed home after Tognozzi headed clearance from Balotelli's corner.
Reggina 2-3 Inter (HT: 1-2)
Scorers: Maicon 9, Vieira 24, Cozza 34, Brienza 53, Cordoba 90+1.
Reggina: 30 Campagnolo; 3 Costa, 5 Cirillo, 55 Lanzaro (13 Cosenza 75), 16 Valdez; 7 Vigiani, 8 Barreto, 35 Carmona; 81 Brienza (31 Tognozzi 82), 10 Cozza (88 Di Gennaro 68), 9 Corradi.
Subs not used: 1 Puggioni, 2 Hallfredsson, 18 Rakic, 20 Alvarez.
Coach: Nevio Orlandi.
Inter: 12 Julio Cesar; 13 Maicon, 2 Cordoba, 26 Chivu (16 Burdisso 75), 6 Maxwell; 4 Zanetti, 14 Vieira; 77 Quaresma (21 Obinna 82), 45 Balotelli, 8 Ibrahimovic, 33 Mancini (18 Crespo 58).
Subs not used: 1 Toldo, 5 Stankovic, 23 Materazzi, 25 Samuel.
Coach: José Mourinho.
Referee: Andrea De Marco (Chiavari).
Booked: Barreto 37, Cordoba 39.