A lethargic-looking Barca crashed to a shock 2-0 defeat at home to promoted Hercules on Saturday, while Inter, who eliminated the La Liga giants in a dramatic semi-final last season, struggled to beat Udinese 2-1.
Barca host Panathinaikos in their Group D opener at the Nou Camp, while Inter start their title defence with a Group A trip to Dutch champions Twente Enschede.
New Inter coach Rafael Benitez has doubts over the fitness of key defender Maicon.
His Barca counterpart Pep Guardiola is looking to his roster of World Cup-winners, including Xavi and Andres Iniesta, as well as World Player of the Year Lionel Messi to shine.
In other Tuesday matches, 2008 winners Manchester United host Rangers in Group C, Schalke 04 play at Olympique Lyon in Group B and Champions League debutants Tottenham Hotspur travel to Bremen to take on Werder in Group A.
Rio Ferdinand will return from injury to shore up United's defence, while striker Wayne Rooney will attempt to put aside recent turmoil in his private life.
Rooney last week appealed for privacy after days of media speculation about his marriage and was left out of the squad for Saturday's Premier League trip to his former club Everton.
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