Holders Real Madrid breezed into the last 16 of the Champions League with two games to spare when a Karim Benzema strike secured a 1-0 win in their Group B match at home to a toothless Liverpool on Tuesday.
Real Madrid's early-season woes deepened when they lost 2-1 at home to La Liga champions Atletico Madrid, while substitute Neymar struck twice in Barcelona's 2-0 win against visiting Athletic Bilbao on Saturday.
Mesut Ozil guided Arsenal to a 2-0 victory over Napoli while a late Cesc Fabregas header gave Barcelona a laboured 1-0 win at 10-man Celtic in the Champions League on Tuesday.
There will be plenty of tension in the air in North London on Wednesday when out-of-sorts Arsenal face Borussia Dortmund seeking to qualify from the Champions League group stage for the 15th successive season.
'I'm very excited to be here. I'm very happy'
Leaders Chelsea have seen their lead reduced to just three points after a shock defeat, and a revival from defending champions Manchester City. Manchester United are back in third after a run of five straight wins. If Chelsea slip agains, City continue to pile on the pressure and United keep the winning momentum it will make EPL battle further interesting.
Ajax, semi-finalists last season, came from behind to beat PAOK 3-2 for a 5-4 aggregate win over the Greeks while Red Star knocked out FC Copenhagen on penalties after a bizarre shootout involving 22 spot-kicks.
News of all that's transpired on and off the football field
Pep Guardiola will return to the Nou Camp in the Champions League group stage after his new club Manchester City were drawn against his former Barcelona team on Thursday. The two sides were drawn in Group C alongside Borussia Moenchengladbach and former European champions Celtic in one of the toughest of the eight sections. Spanish coach Guardiola, who won the Champions League twice with Barca, faced the Catalans when he was in charge of Bayern Munich two seasons ago and suffered a 5-3 defeat in the semi-finals.
Arsenal's young guns continued to shine as they dismantled Standard Liege 4-0 on a hectic night of Europa League action that produced a full house of Spanish victories on Thursday. A summary of the matches.
Sevilla conjured up a dazzling comeback to clinch a record third successive Europa League title on Wednesday, flooring Liverpool with a 3-1 victory that showed why the Spanish side have become masters of Europe's second-tier competition.
News of all that's transpired on and off the football field
The value of an in-form striker was underlined as Tottenham Hotspur, Liverpool and Athletic Bilbao needed goals from pivotal front men to grab vital wins that booked places in the Europa League last 32 on Thursday.
Manchester United are almost certain to reach the knockout stage of the Champions League after they beat Benfica 2-0 at Old Trafford on Tuesday to make it a perfect four wins in Group A.
News of all that's transpired on and off the football field
A summary of sports events and sports persons, who made news on Friday
Manchester United's hopes of salvaging their season in the Europa League suffered a stinging setback when they lost 2-1 at Danish side Midtjylland in the first leg of their last-32 clash on Thursday.
Seven-times champions AC Milan, knocked out of the Champions League by Barcelona in the last two seasons, were drawn against the Catalans again in the group stage of this season's competition on Friday.
Unai Emery's side were heading for a demoralising defeat, three days after losing meekly to Sheffield United in the Premier League, but substitute Pepe's late intervention kept the Gunners top of Group F with a maximum nine points.
Barcelona must to wait to confirm a place in the Champions League last 16 after dropping points for the first time in Group D in an absorbing 0-0 draw at Olympiakos Piraeus on Tuesday.
A summary of all the Champions League matches played across Europe on Tuesday
Lionel Messi marked his first start after injury with a goal in Barcelona's 1-1 draw at AC Milan in the Champions League on Tuesday while Fernando Torres got two as Chelsea thumped Schalke and Atletico Madrid's charge continued.
Coach Pep Guardiola was left thrilled after ManchesterCity revived their Champions League bid by beating his old club Barcelona 3-1 in a gloriously open Group C encounter at the Etihad Stadium on Tuesday.
Liverpool see Tuesday's Champions League game at holders Real Madrid as a chance to prove their doubters wrong and get their season back on track, said coach Brendan Rodgers and midfielder Jordan Henderson.
Images from the UEFA Champions League matches played across Europe on Wednesday
Barcelona and Atletico Madrid led a Spanish Armada into the Champions League last 16 with home wins on Wednesday and in-form Aaron Ramsey steadied Arsenal's boat with a battling win against rocky Borussia Dortmund.
Atletico Madrid sealed top spot in Champions League Group D after second half goals from Frenchmen Kevin Gameiro and Antoine Griezmann but Napoli were held to a 0-0 Champions League draw at home by Dynamo Kiev.
Photos from the Champions League matches played across Europe on Tuesday.
Rafael Nadal is recovering satisfactorily from appendicitis and will continue a course of antibiotics in a bid to be fit for the remainder of the 2014 season, the World No 2's spokesman said on Thursday.