The 19-year-old midfielder marked his senior debut with a superb free-kick as United beat Ipswich 3-0 in the previous round.
Pereira has since gone on to make just one substitute appearance for United's first team, in the Champions League win over Wolfsburg last month
But with boss Louis van Gaal expected to make changes following Sunday's goalless derby draw against Manchester City, Pereira could be handed another opportunity at Old Trafford.
And the young Brazilian will not be afraid to try his luck from outside the box again should the chance arise.
"I hope I get another opportunity and I hope I can show the manager and impress everyone in the stadium and my team-mates," he said in the club's matchday programme, United Review.
"If a free-kick appears and you've been practising, you sometimes have a feeling you will score
You feel confident and it's a very good feeling when the ball goes in.
"I spend a lot of time practising them, but I also try to improve everything, not especially one thing
I practise my free-kicks, my shooting, my dribbling - everything."
United have not lifted the League Cup since 2010, and Juan Mata is determined to end that drought.
The midfielder, whose former club Chelsea claimed the trophy last season, expects a stern test from promotion-chasing Boro.
"Middlesbrough are playing in the Championship, but last season they were really close to being promoted to the Premier League and this year they're again up there," he told the club website.
"It's going to be a good test for us at Old Trafford
I've never won this tournament, I hope we can make it this season."
Antonio Valencia is a doubt for the match after he was forced off towards the end of the City stalemate with a foot injury
United are still without defenders Luke Shaw (leg) and Paddy McNair (liver) but wide man Ashley Young (calf) and striker James Wilson (illness) are close to returning.
Marouane Fellaini, Daley Blind, Memphis Depay and Jesse Lingard could be among those handed starts.
Source : PA
Source: PA