Barcelona and AC Milan lock horns at the Nou Camp in Wednesday night's Champions League Group H showdown with the Italians desperate to put their domestic woes behind them.
Milan go into the match having endured their worst start to Serie A in 31 years.
Saturday's 2-0 defeat to Fiorentina was Milan's fifth loss of the season and left them 11th in the standings with 12 points from 10 games.
"This is the most difficult situation I've faced in my three-and-a-half years at Milan," AC Milan coach Massimiliano Allegri admitted. "I'm responsible for everything.
"We cannot play as bad as we did against Fiorentina.
"We need to come out of this ugly situation.
"In football, results count and we have a week to put things right, starting with the game at Barcelona.
"One thing is clear, we need to give much more because what we've done so far, is simply not enough."
In contrast, Milan's form in Europe has been solid with the Rossoneri unbeaten and chasing first place in the pool against the Spaniards.
Allegri's side stand second in the group with five points, two points above Celtic, who are third.
Rivals Barca are two points clear of Milan and know that a win on Wednesday would see them seal a place in the knock-out round with two games to spare.
"We would love to win because it would place us in a great position in the group," Barca forward Pedro said. "But Milan is a team that has a lot of potential and we cannot take them lightly."
Unlike Milan, Gerardo Martino's Barca have enjoyed a fine start to La Liga.
The Spanish champions are unbeaten and Friday's 1-0 triumph against Espanyol in the Barcelona derby lifted them one point clear of Atletico Madrid in the table.
Lionel Messi will be hoping to end his goalscoring drought against Milan.
The Argentina striker, whose last goal came in a 1-1 draw at AC Milan on October 21, has not found the back of the net in the last four league games - his longest barren spell in two years.
"Leo is ambitious," Barca winger Pedro said. "He always wants to score but honestly, I see him calm.
"He is the best player in the world and the goals will come.
"Leo is not scoring but he is helping the team in other ways by giving assists."
Messi will start alongside Neymar and in-form Alexis Sanchez, whose solitary goal against Espanyol handed his side their third-straight league win.
The hosts will be without Mexican midfielder Jonathan dos Santos, who underwent knee surgery last week.
Milan will be bolstered by the return of defender Philippe Mexes from suspension.
Former Real Madrid midfielder Kaka will play in support of Mario Balotelli and Valter Birsa in Milan's attack.