Daniel Ayala opened the scoring for Tony Pulis’ men after heading past goalkeeper Nick Townsend a corner taken by Lewis Wing.
Mathew Dolan’s injury-time strike offered the visitors a lifeline as they will wait for a replay to determine their Fifth Round fate.
Middlesbrough FC (@Boro) January 26, 2019
But Mikel who joined from Tianjin Teda insisted there was promising aspects to his performance while hoping for more game time.
“I thought the performance was good,” Mikel told club website.
“When you play these games, we were one up, we controlled the game and it’s one of those games where if you sit back you can get caught out and that’s what happened.
“The team played really well, it’s a good start for me and hopefully we can carry on from here.
“Today was good and hopefully I can get a few more games to get sharper and help the team a bit more.”
The Nigeria international would be hoping to make his league bow when Boro travel to promotion-chasing West Bromwich Albion on February 2.