Derby County 0 Sunderland 2
Second-half goals by Stephen Elliott and Dean Whitehead saw off Derby's challenge and consigned the home side to a third home league defeat on the trot.
Sunderland showed why they have an impressive record by closing Derby down and limiting them to just one shot on target.
The closest Derby came to scoring was Inigo Idiakez's free-kick that came back off the crossbar in the 49th minute, two minutes before Sunderland took the lead.
Both sides had rarely posed a threat in the first half although Derby felt they might have had a penalty late on for a trip on Polish striker Grzegorz Rasiak.
But Sunderland always looked to have something extra in reserve and once Elliott had scored in the 51st minute they never looked back.
The visitors broke swiftly down the Derby right, and although Lee Camp saved well from Julio Arca, Elliott beat Michael Johnson to the rebound to score.
The second goal also came down the same channel with Elliott going past Pablo Mills before pulling the ball back to Whitehead whose fiercely-struck shot hit Johnson before rebounding off the Sunderland midfielder and into the net.
If there was an element of good fortune about that goal, Sunderland deserved it for the composure of their overall performance.
They were solid and organised at the back, and although Tom Huddlestone played some good balls through to the front men, they did not have one clear opening in the game.
Sunderland might have scored again late on when Arca went through but although he tumbled over as Camp raced out, the referee decided he had dived and showed him a yellow card.