West Bromwich Albion piled the pressure on Chelsea with a 1-0 victory on Saturday as Premier League leaders Manchester City downed Bolton to open up a five-point lead at the top of the table.
An 82nd minute strike from Gareth McAuley secured all three points for West Brom at the Hawthorns to deal a fresh blow to under-fire Chelsea manager Andre Villas-Boas, reportedly battling to hang on to his job.
The defeat left Chelsea three points adrift of the top four after Arsenal's push for Champions League qualification was given fresh momentum following a dramatic 2-1 win over Liverpool in Saturday's early kick-off.
Elsewhere, leaders City cruised to a straightforward 2-0 win over Bolton at Eastlands courtesy of an own goal from Gretar Steinsson and a Mario Balotelli strike at Eastlands.
The win preserved City's 100 percent home record and left second-placed Manchester United needing to get a result at Tottenham on Sunday to reduce their rivals' lead at the top.