Mike Dodds' second spell as Sunderland's interim head coach began with defeat as Brazilian winger Ronald inspired Swansea City to victory at the Stadium of Light.
A vibrant first-half performance was the key to Swansea's triumph, with Ronald putting them ahead on the rebound after Liam Cullen's header was saved.
Ronald, a January signing from Brazilian club Gremio Anapolis, scored a second goal nine minutes later as he finished expertly after being picked out by Joe Allen.
Swansea might have been out of sight by half-time, with Przemyslaw Placheta hitting the post, before Sunderland's second-half improvement was rewarded when Luke O'Nien headed them back into the contest.