Birmingham City were beaten by two goals of Premier League quality as Tony Mowbray's Sunderland won at St Andrew's.
On-loan Everton striker Ellis Simms scored the Wearsiders' first goal on 25 minutes, set up by fellow loan man Amad Diallo.
Manchester United winger Diallo then scored a stunning second four minutes into the second half to seemingly seal Blues' first home defeat since August.
Substitute Lukas Jutkiewicz gave Blues hope on 78 minutes with his first goal in almost a year, but Sunderland survived late home pressure, including seven minutes of added time.
That was enough to earn Mowbray's men a second straight away win on the former West Brom and Coventry boss' return to the Midlands to lift Sunderland into the top half of the Championship table, within a point of John Eustace's 10th-placed Blues.