Barcelona hold a narrow advantage at the halfway point of the tie after victory at Old Trafford.
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Barcelona are in command of their quarter-final tie against Manchester United, Luke Shaw's early own goal giving the Blaugrana a slender first-leg win at Old Trafford.
Aiming to reach a first semi-final since they last lifted this trophy in 2015, the visitors took the lead inside 12 minutes, Shaw deflecting Luis Suárez's powerful back-post header into his own net.
The hosts rallied after going behind and went close either side of the interval through Diogo Dalot and Marcus Rashford, but were unable to find the finishing touch. Not at their most fluent due to an industrious United display, Barcelona's best chance of the second period fell to Suárez, who shot into the side-netting, but Ernesto Valverde's men will be confident of completing the job on Tuesday.
View from the stadium: Matthew Howarth
United improved considerably after switching from a back three to a back four in the first half, but despite enjoying periods of sustained pressure they failed to create enough opportunities to haul themselves level. After their remarkable win in Paris last month it would be foolish to write them off just yet; as Ole Gunnar Solskjær pointed out after their first-leg defeat in the previous round, mountains are there to be climbed.
Man of the match: Gerard Piqué
From the first moment he was pressed into service, racing back towards his own goal and needing to strain every sinew to beat Rashford to the chance, Piqué knew he was "home". The place where he "grew up" and not only made a huge impact with his personality but only missed out on progression because of the Rio Ferdiand-Nemanja Vidić duopoly. The calm throughout, the aerial battles won, the serenity amid something of a red storm and then the late challenge on Anthony Martial, Piqué gave a signature performance – elegance, determination, athleticism – and a reminder to this Old Trafford crowd what they missed out on.
1: This was the first time Barcelona had opened the scoring at Old Trafford.
2: United have won just two of their last 16 matches against Spanish clubs (D6 L8) – and none of the last seven (D3 L4); at Old Trafford they have won only one of the last nine (D4 L4).
4: United have suffered four defeats in their last six European home games.
4: Barcelona's four UEFA Champions League victories against United have come at four different stadiums – Camp Nou, Stadio Olimpico, Wembley and Old Trafford.
7: This was Barcelona's first win in seven knockout away games (D2 L4), the Catalans having scored just one goal since a 2-0 victory at Arsenal in the 2015/16 round of 16. Wins at Arsenal and United are their sole successes in the last nine such contests, with five defeats.
8: United have scored eight UEFA Champions League own goals, fewer only than Sporting CP and Barcelona (nine).
14: Barcelona have benefited from 14 UEFA Champions League own goals, the joint most in the competition along with Real Madrid and Chelsea.
100: Barça midfielder Ivan Rakitić made his 100th appearance in UEFA club competition.
What does it mean?
Unbeaten in a record 30 UEFA Champions League fixtures on home soil (W27), Barcelona will be confident of ending their recent quarter-final jinx and getting over the line next week to set up a last-four date with Liverpool or Porto. United, who can take heart from their showing after falling behind and reversed a bigger first-leg deficit in the last 16, should look no further than boss Solskjær regarding how to pull off the ultimate Camp Nou heist.
Man. United welcome West Ham on Saturday, before the second leg of this tie three days later. Solskjær's top-four chasing team then have two away games and three home games prior to the close of the domestic season, including the visit of a certain Manchester City.
Boasting an 11-point cushion at the top of the Spanish Liga, Barcelona travel to Huesca on Saturday ahead of Tuesday's second leg at Camp Nou. The Blaugrana then have six more Liga fixtures before the Spanish Cup final against Valencia in late May.