Defender Hayden Coulson has signed a new three-year deal with Middlesbrough which will expire in 2023.
Coulson, 21, made his Boro first-team debut in August's 3-3 draw against Luton Town on the opening night of the Championship season.
He has since played 10 more games for Jonathan Woodgate's side, to add to loan spells at St Mirren and Cambridge.
"He did really well in pre-season and has taken his chance with the first team," Woodgate told the club website.
"He's an example to the young players in our academy and we believe he has a great future at this football club."
Woodgate has extensively used players he previously coached in the academy set-up within his first-team squad, with Coulson, Boxing Day goalscorer Djed Spence and Aynsley Pears featuring in recent months.