The Champions League is back! The action got underway on Tuesday night as Europe's big boys kicked off the 2021/22 campaign.

Manchester United, with Cristiano Ronaldo back in business, were in action at Young Boys of Bern, while holders Chelsea began the defence of their title at home to Zenit. 

Read on, or jump to the game of your choice below, for highlights and match reports of all Tuesday's fixtures.

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Sevilla 1-1 RB Salzburg

Sevilla and Red Bull Salzburg shared the spoils at the Ramon Sanchez Pizjuan as Youssef En-Nesyri was sent off in a match that contained an incredible four first-half penalties. 

A VAR spot-kick was awarded to the Austrians early on, after a free-kick had initially been given, but after being fouled, Karim-David Adeyemi fired his penalty wide of the target. 

The German was then fouled again midway through the first period, with Luka Sucic taking this time and scoring. 

Sucic saw his second effort from 12 yards come off the post before Ivan Rakitic helped Sevilla level with their first penalty of the contest five minutes before the break. 

The hosts' task of finding a winner became much tougher when En-Nesyri was given his marching orders after being booked for diving for a second time in the game, following a laughable tumble in the box on 50 minutes.

Young Boys 2-1 Manchester United

Manchester United’s Champions League campaign got off to a nightmare start as Jordan Siebatcheu’s stoppage-time strike earned Young Boys a famous 2-1 victory against Ole Gunnar Solskjaer’s 10 men in Switzerland.

Three-and-a-half months on from losing the Europa League final to Villarreal on penalties, the Red Devils were on course to return to continental action with a straightforward win after Cristiano Ronaldo’s early opener.

The Portuguese’s 135th Champions League goal came as the returning forward equalled Iker Casillas’ appearance record in the competition, but the 36-year-old will want to forget his 177th match.

Aaron Wan-Bissaka’s 35th minute sending off for a rash challenge on Christopher Martins Pereira changed the dynamics of the game, with Nicolas Moumi Ngamaleu levelling before Siebatcheu struck at the death.

Lille 0-0 Wolfsburg

Ligue 1 champions Lille were frustratingly held by 10-man Wolfsburg at the Stade-Pierre Mauroy. 

The hosts thought they had taken the lead just after the break when Jonathan David netted, only for VAR to disallow the goal as the ball had gone out. 

Midway through the second period Jonathan Brooks was sent off for a second bookable offence but Lille could not capitalise.

Villarreal 2-2 Atalanta

Last season's Europa League winners Villarreal held Atalanta in a see-saw encounter.

Gian Piero Gasperini's side drew first blood through Remo Freuler before Manu Trigueros levelled six minutes before the break.

Atalanta had several chances to score and were left to rue their wastefulness as Arnaut Danjuma, a recent signing from Bournemouth, put the hosts ahead after slotting home Gerard Moreno's through ball.

However, Robin Gosens earned the Italian outfit a point on 83 minutes before Francis Coquelin was sent off moments later for a second bookable offence. 

Chelsea 1-0 Zenit St Petersburg

Romelu Lukaku’s pinpoint header rescued Chelsea’s first match as Champions League holders in a 1-0 win over Zenit St Petersburg.

Belgium hitman Lukaku bagged his third goal in two games and his fourth for Chelsea since his £98million switch from Inter Milan.

The 28-year-old converted captain Cesar Azpilicueta’s hanging far-post cross with a header of stunning accuracy, and that after shrugging aside three touch-tight Zenit defenders.

Malmo 0-3 Juventus

Three first-half strikes saw Juventus ease to victory at Malmo. 

The Swedish side had their tails up early on but couldn't take their chances and were punished when Alex Sandro headed home Juan Cuadrado's cross midway through the first half. 

It seemed like Jon Dahl Tomasson's men were only going to head into the break a goal before quickfire strikes on the cusp of half-time ended the match as a contest. 

First, Alvaro Morata was fouled by Lasse Nielsen and Paulo Dybala converted the resulting penalty. Then it was Morata's turn to get on the scoresheet as he finished deftly beyond Anel Ahmedhodzic.

Moise Kean had a second-half effort ruled out for offside, but Malmo were unable to beat Wojciech Szczesny in their first Champions League group-stage appearance for five seasons.  

Barcelona 0-3 Bayern Munich

Robert Lewandowski scored in his 18th successive game for Bayern Munich as they comfortably saw off Barcelona at the Nou Camp.

The result wasn't quite as emphatic as the 8-2 mauling the Spanish giants were on the end of last year as Bayern ultimately won the 2020 tournament, but the visitors were still utterly dominant.

Julian Nagelsmann's men got the breakthrough their superiority deserved when Thomas Muller's shot from the edge of the box took a huge deflection off Eric Garcia to wrongfoot Marc-Andre Ter Stegen.

Lewandowski doubled the Bundesliga champions' advantage on 56 minutes as teenage sensation Jamal Musiala's strike crashed off a post and into the Pole's path for him to stab home from six yards out. 

The game was done and dusted five-and-a-half minutes from the end as Lewandowski was first to the loose ball after Serge Gnabry had hit the woodwork, sitting Gerard Pique down and rifling past Ter Stegen despite the close attentions of Ronald Araujo.

Dynamo Kyiv 0-0 Benfica

Dynamo Kyiv were deprived a late winner by VAR, as the Ukrainian outfit got their Champions League campaign underway against Benfica. 

Viktor Tsygankov hit the bar in the first half, with Roman Yaremchuk having the visitor's two best chances of the match as both sides pushed for a winner. 

Mykola Shaparenko fired home in stoppage time for Mircea Lucescu's side, but an offside in the build-up robbed the home faithful of a memorable moment.