United needed a good start the Nou Camp this evening to overturn a one-goal deficit from the first leg.
But after just 15 minutes, an Ashley Young mistake gifted Messi the ball, which allowed the Argentinian to nutmeg Fred before curling the ball behind De Gea.
And four minutes later, Barcelona had doubled their lead after a howler from the Spaniard.
Messi picked the ball up on the edge of the box and curled a tame effort at De Gea with his right foot, which the goalkeeper let slip through his hands.
And it’s safe to say United fans weren’t happy with the duo.
“Had barely finished dissecting Young’s error when De Gea did that. Barcelona don’t really need the help, lads,” one said.
“Game over due to two huge mistakes by Ashley Young and David de Gea,” one wrote.
“Rashford didn’t take his chances early, Young mistake, now De Gea. Brilliant,” another said.
“Young & De Gea have basically ruined everything,” a fourth said.
“You couldn’t help but feel that we needed to take those early chances, however tricky – then, oh Young, oh De Gea, game oh-ver,” one tweeted.
“Poor from young first. Then De Gea does that…” added a sixth.
Barcelona have been knocked out of the Champions League at the quarter-final stage each of the last three years.
But the Catalan outfit look well on their way to progressing to the final four after the opening 45 minutes this evening.
In tonight’s other clash, Juventus star Cristiano Ronaldo opened the scoring for Juventus moments after Messi’s second.
The Italian side were soon pegged back by Ajax.