After two defeats since Luis Suarez came into the team, Barcelona seeks to recover Wednesday when the Uruguayan striker returns to Amsterdam to face former club Ajax in a Group F fixture in the Champions League.
Barcelona was beaten 3-1 at Real Madrid and then relinquished the leadership of La Liga on Sunday after a home defeat by Celta Vigo.
Coach Luis Enrique's squad needs to fix defense frailties and a misfiring attack to avoid a third loss since the usually prolific Suarez returned to action after suspension.
In a clash of two four-time European champions, Ajax will hope to repeat itsChampions League victory last season.
Here are some things to know about Wednesday's games:
HAPPY MEMORIES
Suarez will be playing his first Champions League game for Barcelona following suspension for biting Italy defender Giorgio Chiellini at the World Cup.
Suarez played for Ajax from 2007 to 2011. He was club captain and player of the year.
Last year, Ajax beat Barcelona 2-1 thanks to a dazzling first-half attacking display and then determined defending when Joel Veltman was sent off.
"Maybe we should watch the videos of last year," said midfielder Lasse Schone.
Veltman said: "I'm looking forward to the match. It's a great challenge to take on such amazing players."
After losing 3-1 two weeks ago in Barcelona, Veltman believes Ajax must be bold.
"We have to be daring," he said.
Barcelona is second in Group F, a point behind Paris Saint-Germain. Ajax, with two draws and a defeat so far, is third, one point ahead of Apoel Nicosia.
Ajax goes into the match after a 4-0 rout of Urk in the Dutch Cup, but will be without midfielder Thulani Sereno and forward Viktor Fischer.
PSG WITHOUT IBRAHIMOVIC
A win against APOEL should see PSG fans celebrate their club's qualification for the knockout phase if Barcelona beats Ajax.
Zlatan Ibrahimovic will miss the match because a left heel injury that is taking longer to heal than expected. The 33-year-old striker has not played since Sept. 21.
PSG coach Laurent Blanc said the Sweden international could be back for the match against bitter rival Marseille on Sunday.
"He is feeling much better, but he is not yet able to train with the rest," Blanc said. "He's not in pain anymore and that's a good sign."
Ibrahimovic's injury has had less impact than expected as the Parisian club remains unbeaten this season in all competitions.
After a record 7-1 win in Rome, Bayern Munich does not expect another rout Wednesday when it hosts Roma in a home Group E match in the Champions League.
Bayern can seal a place in the knockout stages with a draw. Victory will guarantee first place in Group E.
In the other match, Manchester City needs a win at home to CSKA Moscow to improve its chances of advancing.
Bayern leads the group with nine points from three matches; Roma has four, City two and CSKA one.
Here are some things to know about Wednesday's games:
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ANOTHER RECORD?
Bayern's 7-1 triumph was its biggest away victory in the Champions League. If it wins again Wednesday, Bayern will become the first German team to secure top spot in a group after only four matches.
Atletico Madrid achieved the feat last season and reached the final. There, it lost to city rivals Real Madrid, which could secure first place in Group B Tuesday against Liverpool.
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ANOTHER ROUT?
Bayern players do not expect another rout like the 7-1 victory in Italy.
"Roma has learned something from the first match, they will play differently," said attacking midfielder Mario Goetze. "Our goal is to take three points and make everything clear, but we should not start celebrating too early."
Goalkeeper Manuel Neuer said Bayern would not be complacent. "We know that Roma is a strong team," he said.
David Alaba said Roma will not be afraid: "Surely they will have respect for us, but we will also have respect for them."
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LAMPARD RETURN COULD BOOST CITY
Frank Lampard may return after injury in Manchester City's midfield for its game at home to CSKA Moscow.
City is third in Group E. Victory is essential if Manuel Pellegrini's team is to qualify for the knockout stages.
Lampard missed last month's encounter in which City squandered a two-goal lead and drew 2-2.
"I'm not far off selection," Lampard said. "I've been working very hard to get back because I was really enjoying playing."
City's confidence was boosted Sunday when they beat local rivals Manchester United 1-0 in the Premier League with a second half goal from striker Sergio Aguero.
Porto is in elite company after an unbeaten start to the season and hopes to keep that record intact Wednesday on a tricky Champions League trip to Athletic Bilbao for a Group H game.
Like Chelsea, Paris Saint-Germain, Bayern Munich and Borussia Moenchengladbach, Porto has yet to taste league defeat.
It is also undefeated in Europe this season, but has a poor record historically for away matches in Spain.
Elsewhere, Shakhtar Donetsk hosts BATE Borisov.
Here are some things to know about Wednesday's games:
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HOME FROM HOME
Porto is on top of Group H with seven points from three matches.
Coach Julen Lopetegui knows Bilbao well. He was born nearby and played as a goalkeeper for its archrival Real Sociedad and at regional club Logrones.
His knowledge of Bilbao will be needed to help Porto buck a poor record in Spain.
This shows it has five wins and 14 defeats from 21 matches.
Lopetegui's team was eliminated from its last two European campaigns by Spanish opponents Sevilla and Malaga.
The coach has included Brazilian attacking midfielder Evandro and goalkeeper Ricardo Nunes who have returned to fitness.
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Unbeaten in all competitions this season, Chelsea has been in stellar form and could ensure itself a spot in the knockout stage of the ChampionsLeague with a win on Wednesday.
Victory over Maribor in Group G, along with Sporting Lisbon failing to beat Schalke, would be enough for the London club to advance.
Sporting, looking to turn around its season, is winless in this season's tournament and sixth in the Portuguese league. But the team was denied a point against Schalke in October when Adrien Silva was penalized for handball, although replays showed the ball hit his chest.
Here are some things to know about Wednesday's matches:
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CHELSEA EYES KNOCKOUT STAGE
Chelsea has already beaten Maribor, routing the Slovenian club 6-0 at Stamford Bridge in October, and leads the Premier League by four points.
But Chelsea manager Jose Mourinho will be looking for an improvement on Wednesday after saying his team's "collective performance was not there" in the 2-1 win over Queens Park Rangers on Saturday.
"In the end we deserved to win but the result could've been more than such a narrow result," Mourinho said. "We have to be more consistent and play better."
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SCHALKE'S INJURED
Schalke travels to Portugal without attacking midfielder Julian Draxler, who is out for the year with a hamstring injury. But another midfielder, Kevin-Prince Boateng, should be back.
The absence of Draxler, however, will hurt Schalke's attack. A member of Germany's World Cup squad, Draxler's speed is crucial to Schalke's counterattacks.
Schalke has stabilized under coach Roberto di Matteo, winning three of four games under his guidance.
"You always have to try to score at least one goal away," Di Matteo said. "We want to be organized in defense and then try to execute a few counterattacks."
Schalke has been bolstered by the return of defensive midfielder Jan Kirchhoff from injury, who is on loan from Bayern Munich.
"We are going to Lisbon to win and all but clinch a slot in the knockout round," Kirchhoff said.