The Cameroon international opened the scoring in the 21st minute when he squeezed a shot through the legs of Bremen keeper Tim Wiese before doubling the advantage six minutes later when controlled a Maicon pass before expertly side-footing home.
Wesley Sneijder got a third for the home side in the 34th minute when he coolly lifted an Eto'o through ball over Wiese before the roles were reversed allowing Sneijder to play in the star striker who completed the rout and his treble in the 81st minute by rounding Wiese and finishing into an empty net.
The only downside for Rafael Benitez's Inter was the injury to goalkeeper Julio Cesar who had to be replaced by Luca Castellazzi at half-time.
UEFA Champions League Group AInter Milan (ITA): 4 (Samuel Eto'o 21', 27', 81', Wesley Sneijder 34') Werder Bremen (GER): 0 Venue: San Siro, Milan Crowd: approx. 60,000 Referee: Alberto Undiano Mallenco Yellow cards:INT - nil BRE - Daniel Jensen 44', Sebastian Prodl 64'
INT Julio Cesar (gk) (Castellazzi 45'), Ivan Cordoba, Lucio (Santon 62'), Cristian Chivu, Maicon, Esteban Cambiasso, Dejan Stankovic (Obi 80'), Samuel Eto'o, Wesley Sneijder, Philippe Coutinho, Jonathan Ludovic Biabiany
Subs - Luca Castellazzi (gk) (45'), Sulley Muntari, Alessandro Mancini, McDonald Mariga, Davide Santon (62'), Joel Chukwuma Obi (80'), Felice Natalino
BRE Tim Wiese (gk), Sebastian Prodl, Per Mertesacker, Mikael Silvestre, Wesley, Philipp Bargfrede, Daniel Jensen, Hugo Almeida (Wagner 78'), Tim Borowski (Pasanen 45'), Marko Arnautovic, Marko Marin (Hunt 63')