Middlesbrough moved up to second in the Championship table as goals from Rhys Williams and Marvin Emnes were enough to defeat Derby County.
Williams turned in the opener from close range just before the interval.
And Emnes added the home side's second seven minutes after the break when he headed home Justin Hoyte's cross.
Derby, who hit the woodwork four times, handed a debut to 15-year-old striker Mason Bennett - the youngest player in the club's history.
Lee Holmes had held the record but England Under-16 international Bennett - at just 15 years and 99 days old - ensured his place Derby's history.
He showed glimpses of his talent but was unable to stop the Rams slipping to sixth spot.
Chances arrived at both ends early on with Julio Arca shooting straight at Rams goalkeeper Frank Fielding from 20 yards - and Williams also heading at Fielding from six yards.
At the other end, the lively Bennett headed wide from Theo Robinson's cross and Robinson headed Ben Davies' free-kick wide from close range.
But Boro then began to get on top.
Lee Croft had to scramble an Emnes effort off the line, Scott McDonald twice fired wide and Fielding had to be at his best to turn away Tony McMahon's 18-yard effort.
The pressure finally told when Hoyte's effort was turned into the top corner by Williams.
Derby came back into the game and Robinson was unlucky not to level as Boro keeper Jason Steele pushed the striker's effort onto the post and away for a corner.
Boro then made it 2-0 when Emnes headed in his sixth goal of the season from Hoyte's cross.
McDonald was once again denied by Fielding but Derby could have snatched a point late on.
First Bennett crashed a shot against the bar after Steele parried substitute Chris Maguire's effort.
Then substitute Jamie Ward hit the bar with a 20-yard strike and also saw a cross deflect onto the woodwork late on.