Watford manager Tom Cleverley hailed his youthful back four as they secured a clean sheet, and three points, at Middlesbrough.
After the Hornets picked up just their second win in 11 games, Cleverley told BBC Three Counties Radio: "The average age of our whole back four was 21 so it was a big call from me on the team selection.
"Mattie Pollock has been outstanding for us this season but I felt on Tuesday night (v Leeds) he looked like it had caught up with him a little bit.
"It was a decision I didn't take lightly with it being his home-town game but Kevin (Keben) came in and did fantastic.