Former Middlesbrough striker Jordan Rhodes returned to the Riverside to help Huddersfield to a 2-0 win that keeps their hopes of a top-two finish alive.
Rhodes, who never scored on home turf during his time at Boro between February 2016 and July 2017, set up Naby Sarr's opener four minutes before the break.
And the 32-year-old scored only his second of the season on the hour to secure the victory that keeps Huddersfield in touch with second-placed Bournemouth.
Middlesbrough, who slipped down to eighth, are now without a win in four matches after suffering a third straight league defeat at the Riverside without scoring a goal.