Jensen was tenacious in midfield alongside Christian Norgaard but wasteful in front of goal. The Dane sent a bobbling volley wide in the opening minutes before wasting two golden chances with timid finishes straight at the United goalkeeper, the second coming after he was played through by Ivan Toney at the end of an electric break.
The Brentford No8, who had been superb everywhere but the final third, rolled another one at De Gea minutes before the visitors made him pay for the wasted chances.
United had created hardly anything aside from a hopeful Cristiano Ronaldo header which had landed on top of the crossbar to this point.
Brentford had been well drilled at the back but allowed Anthony Elanga to slip in behind the defence and latch onto a fine ball from Fred. The young Swede took a heavy touch but a moment of indecision from goalkeeper Jonas Lossl allowed Elanga the time to latch onto his own touch and head in his second Premier League goal for the club.
Having been so abject for the majority of this game, United then stung their hosts a second time as Bruno Fernandes raced away on the break and played in Mason Greenwood to tap home.
The Bees pushed for a way back into the game and Raphael Varane had to block an effort from Toney, but it was Ralf Rangnick’s side who killed the contest off on the break moments later.
Scott McTominay won the ball in midfield before finding Bruno Fernandes, who fed substitute Marcus Rashford, the England international unleashing a superb finish into the near post.
Thomas Frank’s side got one back through Toney late on but it was too late to mount a comeback.
Here is how Jack Rosser rated Manchester United…
David De Gea 7
Kept his side in it throughout the first half when everyone else in United colours looked all at sea.
Diogo Dalot 6
Dealt with Sergi Canos well on the right but offered little going forward.
Victor Lindelof 5
Looked shaky at times and often struggled to deal with Ivan Toney’s physical approach.
Raphael Varane 6
Fared better than his partner against Toney and made a good block from the Bees striker in the second half.
Alex Telles 6
Struggled up against Bryan Mbuemo for most of the night and rarely got forward to pose a threat at the other end.
Overrun in the first half but played a fine ball over the back of the Brentford defence to create the opening goal.
Scott McTominay 8
Again, struggled before the break but set the tone for United’s turnaround in the second half. Won the ball to start the move for the second and third goals.
Mason Greenwood 6
Passive in the first half but showed good energy to get into the box and tap in his fifth League goal of the season.
Bruno Fernandes 6
Peripheral figure for the most part before showing great pace and awareness on the break to setup Greenwood’s goal. Wasted a brilliant late chance to score himself with some needless showboating.
Anthony Elanga 7
A few loose touches in the first half but was full of energy and took his goal superbly.
Cristiano Ronaldo 6
Largely an observer throughout the second half, but did well to play in Fernandes on the break for United’s second. Threw a strop when substituted.
Marcus Rashford 7
Fantastic, ruthless finish at the near post to bag his first goal since October.
Harry Maguire 6
Assured on the left of a back three having been a surprise omission from the starting XI.
Nemanja Matic n/a