The Red Devils were trailing 1-0 from the first leg and started brightly against the Catalans, creating chances first through Marcus Rashford and then through Scott McTominay.
However, Barcelona survived the first 15 minutes and scored twice in four minutes through Lionel Messi to effectively kill the tie.
Messi was a peripheral figure at Old Trafford but he capitalised on mistakes in Uniteds defence to send the Red Devils crashing out.
And Mourinho believes that Solskjaers decision to attack Barcelona cost United dearly as they gave up space in midfield for Messi to exploit.
I think the United approach was different, Mourinho told Russia Today.
In the first leg they tried to occupy that central zone. Messis position is easy to understand but it is not easy to create a cage to control him. He comes from the right, then stays in the middle, then Rakitic goes right and allows him to stay in the middle. Its very difficult.
Manchester United in the first match zonally they occupied that area very well. When he came into the inside he was finding Fred, he was finding McTominay coming to the inside all the time.
But I think in this match because United were losing 1-0 they tried to start with a different perspective.
Now it was Pogba wide left, McTominay much more on the right and Jesse Lingard starting as a 10 behind the strikers. In front of the defensive line was only Fred. Thats the area that Messi comes to get the ball and when Messi has the ball..one, one, one…you are dead.
Thats why I never liked individual man-on-man against Messi. Messis a cage, you have to create a cage. Barcelona is Barcelona, they have better players than Manchester United. I think its normal they won.
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