Pereira was one of eight united players who were told that they had no immediate future under the Portuguese two weeks ago.
United are said to be only wiling to sanction a loan deal for the talented youngster and do not want the 20-year-old to leave the club on a permanent basis.
Mourinho wants the Brazilian to go out and gain more first team experience away from united and would like the youngster to have a full season of games under his belt, before he is considered for his first team plans at Old Trafford.
Boro were said to have been interested in taking Pereria to the Riverside at the back end of last season on an emergency loan, but a deal failed to materialise.
The top-flight new boys have recruited significantly over the summer under the guidance of Victor Orta and he is keen to add more new faces to his squad before the transfer window slams shut, starting with Pereria.
In moving to the Riverside, Pereira would almost guarantee himself first team football enabling him the chance to show the world what he is all about. Staying at Manchester United to feature in the odd domestic cup game and the Under-21 side would not be fair on Pereira nor anyone else.
For a player as talented as he is to be wasting away in the Under-21’s every week would be a crime, not only for him, but for football.
It’s disaster for Manchester United as they are dumped out of the Capital One Cup by Championship side Middlesbrough on penalties.
Manchester united started the game with plenty of possession but again failed to create many goal scoring chances. The play at times was frustrating with lot’s of passes not finding their targets and runs down the wing coming to nothing.
United were forced to wait until the 34th minute for their first shot on target when James Wilson found himself with a scoring chance but his shot was straight at Mejias.
On the 40th minute United had another chance to score when Daley Blind played a diagonal cross to Fellaini who chested the ball down, allowed it to bounce and hit the volley but he was quickly closed down and the volley blocked. Fellaini also had another chance earlier in the half but he scuffed the shot dragging the ball wide.
A resilient Middlesbrough also had there chances.
Their first chance came on the 15th minute when a mis-timed overhead kick from Nsue fell into the path of Friend, who’s shot was saved by Sergio Romero.
Just before half time Middlesbrough came close again when Stuart Downing rifled a shot from outside the box but it was no problem for Romero who reacted quickly to tip it over the bar. A couple of minutes before that Kike also had a scoring chance after bringing down an Ayala cross. But he was unable to get any real purchase on his effort and it was a simple save for Romero.
The second half was a far more entertaining half with both sides having plenty of goal scoring opportunities.
Manchester United were the team who started the brightest. On 52 minutes, Memphis, cutting in from the left and hit a low driven shot but the Middlesbrough keeper got down quickly to stop it.
Pereira and Fellaini also had chances to put Manchester United ahead just a few minutes later but their shots were also lacking as they were both straight at Mejias.
On 57 minutes Middlesbrough thought they had taken the lead when Daley Blind turned a bizarre clearance, from a rebound off the post, into his own net. The goal, however, was disallowed as Kike was in an offside position when he hit his shot against the post.
Six minutes later Middlesbrough again, thought they were going to take the lead after Sergio Romero failed to control a back pass from Daley Blind. The ball rolled of the United keepers foot, hit the outside of the post and ran out for a corner.
The visitors had another chance on 67 minutes. Stuart Downing played a perfectly weighted through ball into the box finding Leadbitter. Leadbitter then fired in a shot from a tight angle but Sergio Romero got down quickly to turn the ball out for a corner.
Then it was Manchester United’s turn again.
Between the 80th and 90th minute, United a managed few attempts at the Middlesbrough goal. Fellaini and Smalling failed to hit the target with their efforts but Jesse Lingard came mighty close in the 90th minute with a fantastic volley that ricocheted off the post.
It looking as though United were going to snatch a winner. But Middlesbrough were not done yet.
In the space of a minute (90-91), Middlesbrough had three shots on goal, two of which were from Stuart Downing who forced two good saves from Sergio Romero.
Unfortunately neither team were able to find a winner in normal time so the game went to extra time in which both teams had great chances to snatch a winner.
The best chances for a winner came for United in the dying seconds of the second half (ET). The first fell to martial who watched his diving header bounce just in front of the goal line but the spin took it the wrong side of the back post.
A minute later, in time added on, Jesse Lingard played a cross into the box. Fellaini got his head to the ball with space around him and only the keeper to beat. Unfortunately he could only direct the ball over the bar.
The game then went to penalties and misses from Wayne Rooney, Michael Carrick and Ashley Young cost Manchester United the game with Middlesbrough winning the shoot-out 3-1.
As a neutral, this would have been a fantastic game to watch with so many late chances in normal time and extra time for both teams. For United fans however, it will be another frustrating experience. Once again Wayne Rooney failed to impress; big money signing Memphis also had another game he will want to forget quickly and again they failed to break down a solid defence.
What did you think of the game? We would love to hear your thoughts in the comments below. Or you can visit The United Stand Fan Forum here to join the post match discussion.
You can also watch the Manchester United V Manchester City match reaction on The United Stand’s YouTube channel by clicking here or watching below.