Sunderland are currently level at 1-1 with Chelsea at the interval of their Premier League clash at Stamford Bridge.
Chelsea started on the front foot and came close to taking the lead in the fourth minute when Didier Drogba met a cross from Juan Cuadrado, but the honorary Blues skipper could not find the back of the net.
The opening 10 minutes all belonged to Chelsea, with the party atmosphere inside the stadium making it difficult for Sunderland to make their mark against the champions.
The visitors came close to breaking the deadlock in the 13th minute when Sebastian Larsson tried his luck with a 25-yard free kick, but his dipping effort was pushed away by Petr Cech on what could be his final appearance in a Chelsea shirt.
Branislav Ivanovic then came close for the home side down the other end, but Vito Mannone was alert to make a smart save.
It was Sunderland that took the lead, however, with Steven Fletcher heading a deep Adam Johnson corner home at the back post in the 25th minute.
Chelsea were then forced to substitute Drogba on what was his final appearance in a Blues shirt, with the Ivorian leaving the field for Diego Costa.
The hosts were awarded a penalty in the 35th minute when John O'Shea felled Cuadrado, and Costa stepped up to finish into the corner and level the scores with his 20th league goal of the season.
