Manchester United were given a troublesome tie against Club Bruges in the draw for the Champions League playoff round on Friday, although it could have been worse as they avoided Lazio, CSKA Moscow or Monaco.
Napoli began their Europa League group stage campaign in scintillating fashion.
Top two teams in each group qualify for the first knockout round. Third placed team to play in the UEFA Cup.
UEFA Cup holders Shakhtar Donetsk thrashed Club Bruges 4-1 away on Thursday when top-level football began experimenting with five-man refereeing teams in the opening Europa League group stage games.
A round-up of the UEFA Champions League last-16 first leg matches played on Tuesday.
In other Champions League matches, Manchester United beat Scottish champions Rangers while Chelsea impressed while beating Lazio.
2004 Champions League finalists Monaco were eliminated 2-1 on aggregate by Swiss side Basel.
Leicester City face the latest challenge of Claudio Ranieri's remarkable managerial reign on Saturday, to come back down to earth from the high of a Champions League win for a domestic game against Burnley.
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Leicester City striker Jamie Vardy has said the club will look to enjoy competing against Europe's elite in their Champions League debut. The English champions were drawn in Group G along with Porto, Club Bruges and FC Copenhagen in the Champions League after winning the English top-flight title for the first time in their history.
Last season's runners-up Liverpool, big-spending French league champions Paris St Germain and Carlo Ancelotti's Napoli were thrown together in the pick of the groups while holders Real Madrid must face last season's semi-finalists AS Roma.
At the start of the season Leicester City fans could hardly have imagined their side would take the Champions League by storm.
"It is different to play midfield and striker but I enjoy all the positions I can play," the former Everton midfielder added.
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.
Former European champions Ajax Amsterdam and Celtic, who both suffered the indignity of being knocked of the Champions League qualifiers by underdogs this season, will meet in the Europa Leagueafter being drawn together in the group stage on Friday.
Costa, Alba excluded from Spain squad
Atletico Madrid were handed a chance to avenge last season's Champions League final defeat by city rivals and record 10-times winners Real after the two sides were drawn together in the last eight on Friday. Paris St Germain and Barcelona were paired together having met in the group stage, with the French side winning in Paris and the Catalans coming out on top in Spain.
Manchester United have signed Leicester City's England centre back Harry Maguire on a six-year contract, the Manchester club announced on Monday.
On a night of close finishes in all five first-leg playoff games, the 21-year-old Dutch winger opened his United account with a memorable performance in the famous number seven shirt previously worn by George Best, Eric Cantona and David Beckham.
Manchester United are feeling the pressure ahead of their Champions League qualifier against Club Bruges on Tuesday, according to manager Louis van Gaal.
Old Trafford rejoiced on Tuesday in anticipation of their next famous No. 7 after Dutch forward Memphis Depay scored two sublime goals to inspire Manchester United to a 3-1 victory over Club Bruges.
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.
Iniesta has spent all of his senior career at Barcelona and is their most decorated player ever along with Lionel Messi, having lifted 31 trophies, which is soon to be 32 if Barca clinch the Liga title on Sunday at Deportivo La Coruna.
Bobby Zamora and Bjorn Helge Riise twice combined to set Fulham on their way to a 3-2 win at snowy Basel on Wednesday, sealing the London club's berth in the final 32 of the Europa League. Hertha Berlin, in last place in the Bundesliga, scraped through thanks to a 1-0 win at home to Group D winners Sporting and Panathinaikos of Greece secured second place in Group F when Djibril Cisse scored two in a 3-0 win over Dinamo Bucharest.
Klopp has led Liverpool to back-to-back Champions League finals but is adamant that their impressive recent track record does not make them the title favourites.
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Images from the Champions League matches played on Tuesday
Leicester City added another tale of remarkable success to an incredible year by reaching the last 16 of the Champions League in their debut season with a 2-1 victory over Club Bruges.
Napoli put a foot in the Europa League semi-finals with a perfectly crafted 4-1 win at VfL Wolfsburg on Thursday as Marek Hamsik scored twice in an Italian masterclass to bring cheer to beleaguered coach Rafael Benitez.
Fiorentina tore apart Italian rivals AS Roma to reach the Europa League quarter-finals with a 3-0 win that left their opponents' season in tatters and under-fire coach Rudi Garcia tottering on the brink of the sack.
Leicester City has a chance to go top of the English Premier League table with a maximum nine points.
Manchester United ended their one-year Champions League hiatus in emphatic style when Wayne Rooney struck a hat-trick in a 4-0 destruction of Club Bruges that sent the three-times winners through 7-1 on aggregate on Wednesday.
Images from Champions League matches played across Europe on Tuesday
Since winning 2-1 at home to Wolfsburg in September, United have scored only twice in three Champions League games. In the Premier League the record is five goals in the last six games.
Galatasaray win 22nd Turkish title after beating closest rival
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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.
News of all that's transpired on and off the football field