In a fantastic twist of fates, the duo make their Champions League debuts for their new clubs against their former employers in a Group F clash.
Inter coach Jose Mourinho, a former Barca assistant who angered the Catalans with his antics in previous Champions League ties when Chelsea boss, has been his usual cheeky self.
"Eto'o is the best attacker in the world. My players are always better. Last year Ibrahimovic was the best forward in the world, now I say Eto'o," he told reporters.
Ibrahimovic was the inspiration for Inter's last three Italian titles and at times they depended too much on the tall Swede, although success was elusive in the Champions League.
With Eto'o immediately striking up a good partnership with fellow new signing Diego Milito, Mourinho thinks his side is now more complete and can finally make a mark in Europe.
Inter were dynamic in last month's 4-0 victory over AC Milan while Eto'o scored a superb goal in Sunday's 2-0 win over Parma.
BIG HUG
A sold-out San Siro will want to see more proof of progress on Wednesday even if Ibrahimovic's return will be the big focus.
"From me he will receive a big hug, from the fans I don't know," Mourinho added. "I will embrace him at the start of the match but for 90 minutes I don't even want to know his name.
"We are opponents but I don't feel betrayed. Thanks to him we are Italian champions."
Eto'o is extra keen to beat the holders after clashing with coach Pep Guardiola over his sale but he has played down the obvious comparisons with Ibrahimovic.
"It is us against them not me against him. I'm not going on the field alone," said the Cameroonian, who scored when Barca beat Manchester United 2-0 in the final in May.
Ibrahimovic, who has fitted in quicker at in-form Barca than many predicted, has only limited use as an in-house spy.
"Guardiola has all the information he needs. I tell him what I know but they have quite a few new players and I don't know them all," he told a news conference.
"I think both teams are well prepared. You have to be well informed because often it's the small details that can decide the outcome of games."
As if the battle between the Italian and Spanish champions was not juicy enough, Barca left back Maxwell meets his former club while Inter midfielder Thiago Motta hopes to do the same unless the fit-again Dejan Stankovic takes his place.
Barca's wizard Lionel Messi will also be up against tough-nut fellow Argentines Walter Samuel and Javier Zanetti.
Probable teams:
Inter Milan: 12-Julio Cesar; 13-Maicon, 25-Walter Samuel, 6-Lucio, 26-Cristian Chivu; 4-Javier Zanetti, 5-Dejan Stankovic, 8-Thiago Motta; 10-Wesley Sneijder; 9-Samuel Eto'o, 22-Diego Milito
Barcelona: 1-Victor Valdes; 2-Daniel Alves, 5-Carles Puyol, 3-Gerard Pique, 19-Maxwell; 6-Xavi
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