Duncan Watmore scored twice for the Teessiders before Yan Dhanda pulled one back for the visitors in the second half.
Our Boro writer Joe Nicholson has dished out his marks from the match – scroll down and flick through the pages of our picture gallery to see them:
5. Djed Spence - 7
A few flashes going forward in the first half. Made an important block in the second and saw out his defensive duties. 7 Photo: Getty Images
6. Marvin Johnson - 7
Played a neat reverse pass to assist Watmore’s opener and kept tabs on Swansea full-back Connor Roberts. 7 Photo: George Wood
7. Sam Morsy - 7
Tenacious in midfield on his return to the side. Broke up play and even had a chance to score when found himself in the box following a set-piece. 7 Photo: Alex Pantling
8. Jonny Howson - 7
The deepest of Boro’s midfielders in the first half. Was up against the lively Kasey Palmer but helped keep the Swans at arm’s length. 7 Photo: Getty Images