CATANIA - Inter were tested to the max at the Stadio Massimino as José Mourinho's men were sent to their first defeat in eighteen games.
Diego Milito scored his nineteenth of the season to put the Nerazzurri in front but Maxi Lopez equalised before a Giuseppe Mascara penalty after the dismissal of Muntari and a solo effort from Jorge Martinez gave the home side a famous victory.
It was never going to be easy down in Sicily. The Rossazzurri defended in numbers and looked dangerous coming forward, but their finishing was off the mark in a first half which saw Ricchiuti waste two good chances.
Inter's best opportunity of the opening half fell to Sneijder who forced a punched block from Andujar with a terrific 20-yard drive.
The introduction of Quaresma for Mariga at the interval gave Inter a more attacking dimension and the Portuguese treated us to a trivela cross and some pacy dribbling before setting up Sneijder who saw his shot blocked by Terlizzi.
Inter broke the deadlock nine minutes after the break when Sneijder served Eto'o with a precise lofted pass and the Cameroonian beat the offside trap and unselfishly squared for Milito to slot past the despairing dive of Andujar.
Sneijder found the side-netting as Inter looked to kill off the game with a quick second goal, but after a stuttering start to the second half Catania attacked with renewed belief and cancelled out Milito's opener in the 74th minute when Maxi Lopez got in behind Lucio to convert a low cross from Alvarez.
Inter used up their remaining two substitutions after the Rossazzurri's equaliser, bringing on Pandev for Stankovic and Muntari for Cambiasso.
The Ghanaian midfielder's presence on the pitch lasted all of two minutes, during which he was booked for a foul on Martinez and then sent off for handling Mascara's shot from the resulting free kick. Referee Valeri had no hesitation in pointing to the spot and Mascara stepped up to put his side in front with a cucchiaio penalty kick.
Catania added insult to injury in the last minute when Martinez slipped past Lucio on the left and took the ball round Julio Cesar before slotting into an open goal to send the home fans into delirium.
Inter's last defeat away to Catania came 44 years ago on 20 February 1966. The Nerazzurri went on to win the Scudetto that year.
Catania 3-1 Inter (HT: 0-0)
Scorers: Milito 54, Maxi Lopez 74, Mascara (pen) 81, Martinez 90.
Catania: 21 Andujar; 22 Alvarez, 23 Terlizzi, 6 Silvestre, 33 Capuano (2 Potenza 88); 19 Ricchiuti (4 Delvecchio 76), 27 Biagianti, 13 Izco; 25 Martinez, 11 Maxi Lopez (5 Carboni 84), 7 Mascara.
Subs not used: 30 Campagnolo, 8 Ledesma, 15 Morimoto, 18 Augustyn.
Coach: Sinisa Mihajlovic.
Inter: 12 Julio Cesar; 13 Maicon, 6 Lucio, 23 Materazzi, 4 Zanetti; 5 Stankovic (27 Pandev 77), 19 Cambiasso (11 Muntari 79), 17 Mariga (7 Quaresma 46); 10 Sneijder; 22 Milito, 9 Eto'o.
Subs not used: 1 Toldo, 21 Orlandoni, 2 Cordoba, 15 Krhin.
Coach: José Mourinho.
Referee: Paolo Valeri (Rome).
Booked: Biagianti 24, Zanetti 45, Stankovic 51, Martinez 76, Muntari 80, 81.
Sent off: Muntari 81.