Diego Costa proved the difference as Chelsea finally broke down West Brom to secure the 1-0 victory which moved them back to the top of the Premier League table.
The striker profited on an error from veteran West Brom defender Gareth McAuley, before rifling an unstoppable shot past Ben Foster with 14 minutes remaining, on an afternoon where Antonio Conte's side had been frustrated by the men from the West Midlands.
The Blues were far from their best but their desire and work rate, as well as the introduction of Cesc Fabregas, helped them back to the top.