Chelsea moved six points clear at the top of the Premier League as Cesc Fabregas’ first-half goal beat a stubborn Sunderland at the Stadium of Light.
Fabregas steered into the far corner from the edge of the box as the Blues recorded a 10th consecutive league victory.
Sunderland keeper Jordan Pickford saved from former Black Cat Marcos Alonso and Willian to prevent Chelsea from winning by a bigger margin.
The hosts, who had set up to try to nullify their opponent’s attacking strength, had few chances although they could have snatched a point in injury time but Thibaut Courtois superbly denied Patrick van Aanholt.
It was a hard-fought and important win for Chelsea after Arsenal slipped up against Everton on Tuesday and means Antonio Conte’s side will be top of the table at Christmas.
A key element of Chelsea’s run of recent victories has been consistency with Conte having named an unchanged side in eight of the nine games prior to the trip to Sunderland.
Liverpool boss Jurgen Klopp had recently suggested that Chelsea’s good run could falter when either Eden Hazard or Diego Costa picked up an injury, and Wednesday’s game provided an opportunity to see whether that would be the case.
Hazard did not travel after picking up a knock in Chelsea’s 1-0 win over West Brom at the weekend, so he was replaced by Willian. Conte also took the opportunity to rest Nemanja Matic as Fabregas made his first start since 3 December.