The Sunderland Echo reports that the 24-year-old is set to move to the Stadium of Light on a season-long loan deal.
Sung-Yeung joined Swansea for £6million just 12 months ago, but has fallen down the pecking order at the Liberty Stadium.
The midfielder had been linked with moves to the Championship and the Bundesliga, but now looks set to become Sunderland’s 12th signing of the summer.
