The-19-year-old marked his United debut with a superb free kick in the 3-0 win over Ipswich in the previous round. He is expected to start his second game for United tonight.
"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," Pereira told Manchester United's official 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."