We profile three men who've played for both clubs.
Brazilian defender Emerson Thome signed for Chelsea from Sheffield Wednesday in 1999 but only spent nine months at Stamford Bridge after finding it difficult to break up the central defensive pairing of Marcel Desailly and Frank Leboeuf.
The Blues let Thome join Sunderland - having played just 21 league games for Chelsea - at the start of the 2000-01 season and the Brazilian went on to make 52 appearances in an injury-hit spell on Wearside.
He made his Sunderland debut in a 1-1 draw with West Ham United at the Stadium of Light in 2000 and went on to score twice in Sunderland colours; scoring the winner in a 1-0 win over Coventry City in 2000 before grabbing a late equaliser in 1-1 draw with Aston Villa on New Year's Day in 2002.
After his time with Sunderland finished, Thome joined Bolton Wanderers before spells with Wigan Athletic and Derby County.
Sunderland legend Pop Robson spent three spells on Wearside after starting his career with fierce rivals Newcastle United.
One of the most prolific strikers of his generation, Robson played 206 league games for Newcastle scoring 82 goals before moving to West Ham United and scoring 47 times in 120 games for the Hammers.
His first spell at Sunderland proved successful; he was the club’s top scorer in the 1974-75 campaign before repeating the feat the following term when Sunderland won the Second Division championship.
He then re-joined West Ham in 1976 before returning to Wearside in 1979 where he would spend another two years before joining Carlisle United and eventually Chelsea.
He spent a year as Chelsea player-coach, scoring three goals in 15 appearances.
Israeli defender Tal Ben-Haim moved to Britain after impressing for Maccabi Tel-Aviv in his native Israel.
He was snapped up by Bolton Wanderers in 2004 and made 110 appearances for the Trotters before joining Chelsea in 2007.
He played 20 times in his first season with the Blues before first-team opportunities became limited, at which point he signed for Manchester City at the end of the 2007-08 campaign.
Again, Ben-Haim struggled to establish himself in the first team and, as a result, he joined Sunderland on loan in February 2009, making five appearances before returning to City.