MADRID: Barcelona's dream of retaining the Champions League trophy for the first time is on the line on Tuesday when they face a must-win Group F match against unbeaten Inter Milan and defeat could see the holders crash out of the competition. Barcelona have been undone in their past two matches taking a point from six against Russian champions Rubin Kazan and have a decisive week in their season with the Inter game followed by 'El Clasico' at Camp Nou against Real Madrid on Sunday. If Barcelona lose to Inter and Rubin beat Dinamo Kiev, the defending champions will be eliminated in a group where all four sides can still progress. Just two points separate top from bottom with Inter Milan leading the group a point ahead of Barca and Rubin Kazan with Dinamo Kiev a further point back. Inter boast Barcelona old boy Samuel Eto'o who has an emotional return to Camp Nou having only left the club in the summer. The home fans and players will certainly know all about the threat posed by the Cameroon striker who bagged an impressive 109 goals in 144 league appearances, signing off with 30 in the league last season. "I really miss Camp Nou where I had more good times than bad," said Eto'o. "When I left for Inter I never thought I would play in the stadium again and I am glad to go back." Eto'o insists he bears no grudge towards Barca for allowing him to leave and vowed not to celebrate if he scored out of respect to the fans that once adored him. "I left Barca with a clear conscience and I can't have thoughts of revenge simply because of the friends I left behind there," said Eto'o. "I will try to score because it is my job to do so. However, if I do score I won't celebrate." Barcelona swapped Eto'o and a chunk of change for Zlatan Ibrahimovic in the summer although the Swede is a doubt against his old club with a thigh injury that kept him out of Saturday's 1-1 draw at Athletic Bilbao. Argentine Lionel Messi is also a doubt for the game with a thigh injury sustained against Bilbao while Yaya Toure and Eric Abidal have been struck down with swine flu. "What is worrying me is how to get the players to recuperate. I need players who are fit," said Barca coach Pep Guardiola. "What can we do? Just stop? The fans have to understand that we will play with the players that are fit." It has come at the worst possible time for Barca in a week that could shape their season and centre-back Gerard Pique admitted for now Inter were the top priority. "The Clasico against Madrid is very important but at the moment I think the Champions League match against Inter is more important," said Pique. "Any team that wants to win titles has to stand up and be counted against the great sides." Serie A leaders Inter are unbeaten in the Champions League - although they have drawn three of their four matches - and coach Jose Mourinho, who used to work as a translator at Barcelona earlier in his career, expects a tough game. "The Barcelona game will be a real test for my players," confessed Mourinho. "The Champions League is such a difficult competition where you meet teams with such quality that it's hard to say if it's better to finish the group in first or second position." When the draw was made Barca and Inter were expected to be the two to progress from Group F but both are still scrambling to reach the knockout phase with two games left. Barca have a cold trip to Dinamo Kiev in their final group match while Inter are at home to surprise package Rubin.