Nigeria international Victor Obinna dashed Sunderland's Carling Cup dreams as West Ham tasted victory against Barclays Premier League opposition for the first time this season with a 2-1 win.
The 23-year-old struck 14 minutes after the break to send the Hammers into the fourth round courtesy of a deserved win at the Stadium of Light.
They took the lead with 35 minutes gone when Frederic Piquionne rounded Simon Mignolet to fire home.
The Black Cats were indebted to their Belgian goalkeeper when, having already denied both Obinna and Piquionne in quick succession, he kept out Scott Parker's effort from point-blank range.
Club record signing Asamoah Gyan briefly restored order with a 41st-minute header, his second goal in his first start for the club following a £13million-plus move from Rennes.
However, the Wearsiders were a shadow of the outfit which took a point from Arsenal at the weekend and they surrendered tamely in front of a disgruntled crowd of 21,907.