Ibra & Messi fighting to be fit for Inter
A defeat for the European champions, combined with a victory for Russia's Rubin Kazan over Dynamo Kiev, would see Pep Guardiola's side dumped out of the competition at the first stage as they lie third in Group F with two games left to play.
Messi picked up a thigh muscle injury in Saturday's 1-1 La Liga draw at Athletic Bilbao, which saw Barca knocked off the top of La Liga by arch-rivals Real Madrid.
But tests on Sunday showed the injury was not as bad as first thought, and the Argentine forward could still feature on Tuesday, the club said in a statement.
Sweden striker Ibrahimovic, who missed the trip to Bilbao with a thigh strain, has improved and although he did not train with the squad on Sunday is close to making his return.
Defender Eric Abidal and midfielder Yaya Toure have been struck by the H1N1 virus and defender Rafael Marquez also missed Saturday's game with suspected swine flu, although tests on Sunday showed the Mexican did not have it and he could be available on Tuesday.
Guardiola refused to ring the alarm bells over his mounting problems.
"If players aren't there... we'll play with others. You don't win titles with two or three players," he said after the Bilbao game.
"On Tuesday we play Inter and we can't be saying so-and-so is injured or has the flu. The stadium should be full, without an empty seat, and let's get on with it."
With a top-of-the-table clash at home to Real next Sunday, however, Barca need to improve their effectiveness in front of goal after picking up three draws in their last five outings in all competitions.
Serie A and group leaders Inter will have former Barca striker Samuel Eto'o back in the starting lineup after the Cameroon international was a substitute in Saturday's 3-1 win at Bologna.
Ex-Real Madrid playmaker Wesley Sneijder, who scored the late winner in their 2-1 comeback win at Dynamo Kiev, may return after missing the Bologna victory with a knock.
Former Barca midfielder Thiago Motta could also feature having impressed for Inter of late after coming back from niggling injuries.
"Eto'o will be a starter in Barcelona," Inter coach Jose Mourinho told reporters, with red-hot Diego Milito set to partner Eto'o upfront.
"The most important thing will be our minds, not the tactics or technique. Going there and playing to test our personality is the most important aspect."
Mourinho was also convinced former Inter frontman Ibrahimovic would return for the game: "He is 99.9999% sure to play."
Inter fans worried the side would badly miss the tall Swede after his pre-season swap deal with Eto'o but if anything the Serie A champions have looked more effective without him, passing to create chances rather than hitting long balls.
Ibrahimovic received a mixed reception on his return to the San Siro in the goalless draw in the first group game but Eto'o is expected to receive a warmer welcome from the Catalans.
Barcelona: 1-Victor Valdes; 2-Daniel Alves, 3-Gerard Pique, 5-Carles Puyol, 19-Maxwell; 6-Xavi, 16-Sergio Busquets, 15-Seydou Keita; 10-Lionel Messi, 9-Zlatan Ibrahimovic, 14-Thierry Henry
Inter: 12-Julio Cesar; 13-Maicon, 25-Walter Samuel, 6-Lucio, 26-Cristian Chivu; 4-Javier Zanetti, 19-Esteban Cambiasso, 8-Thiago Motta; 5-Dejan Stankovic; 22-Diego Milito, 9-Samuel Eto'o
Referee: Massimo Busacca (Switzerland)