United's preparations for the new season continued apace with an impressive Tour win over the reigning European and La Liga champions in Santa Clara on Saturday.
Barcelona may have been without the talents of Lionel Messi and Neymar, but they still named a strong side with seven of the XI having featured in the Champions League final six weeks ago.
Luis Enrique's side started on the front foot and almost went ahead in the fourth minute through Luis Suarez, who thumped his effort off a post from a free-kick.
David de Gea, playing in his first match of Tour 2015, saved well from Sergi Roberto before United took an eighth minute lead through Wayne Rooney's header from Ashley Young's corner.
The latter went close again when his well-hit effort was tipped over by Marc-andre Ter Stegen, and Rooney also called the keeper into action with a low effort that was pushed behind in a flurry of United chances.
Our old enemy Suarez was in the mood to be a pain to United again, and he rattled the woodwork for a second time when his 30 yard scorcher crashed off the post with De Gea beaten shortly before the break.
The Reds performance was hugely pleasing but the one slight concern was the wobbly performance of Daley Blind, who again started at centre-back which, to be fair to the Dutchman, is not his preferred position.
Ivan Rakitic smashed a good effort narrowly over the bar and Suarez had a goal chalked out for offside, before United went 2-0 having made a raft of changes (in fact, the entire XI) just beyond the hour mark.
It was a goal straight out of the club's academy, as James Wilson and Tyler Blackett linked up to play in Jesse Lingard, who swept in a well-taken finish from close range.
Adnan Januzaj fired wide and Lingard again went close, but Barcelona kept coming and struck the woodwork for a third time.
Substitute Ivan Rakitic- a scorer in that Champions League final- whipped in a free-kick from the left and young striker Munir headed against the post.
Rakitic shinned the ball wide from Sandro's cross and then forced Sam Johnstone into a good save as Barca pressed in the closing stages.
They finally got the goal their performance merited when Rafinha crashed home a brilliant volley, only for Januzaj to make sure of the win for the Reds in the dying minutes when he ran through and smash home left-footed.
Barcelona may have been missing Messi, Neymar, Dani Alves and a few others for a pre-season game that means nothing, so whilst its important not to get too carried away in the game's global standings, the manner of the Reds performance (and the young players in particular) will send out a hugely positive statement of intent.