London - Chelsea manager Andre Villas-Boas' problems mounted on Saturday after his side laboured to a 1-1 draw with lower league Birmingham in their FA Cup fifth round tie.
Daniel Sturridge headed home a second-half equaliser to save Chelsea's blushes at a restive Stamford Bridge after David Murphy had fired Birmingham into a shock lead on 20 minutes.
Villas-Boas' position has come under scrutiny following reports of a training ground mutiny by his senior players after last weekend's Premier League defeat against Everton at Goodison Park.
His team have now won just one game in their last six games across all competitions and Villas-Boas was forced to watch as his side were booed off the field following another unconvincing display.
Birmingham's opener owed everything to poor Chelsea defending from a set piece.
Nathan Redmond's corner eluded a clutch of blue shirts to bounce across the six-yard box and found Murphy at the back post who prodded home for 1-0.
Chelsea were presented with a golden chance to equalise within seconds, when from the restart Wade Elliott conceded a penalty with a clumsy hack on Ramires.
Juan Mata stepped up to take the spot-kick but Colin Doyle in the Birmingham goal guessed correctly and parried the Spaniard's shot onto the post to preserve the visitors lead.
Doyle frustrated Chelsea once more on 34 minutes, the Birmingham keeper parrying away David Luiz's free-kick as the Brazilian's curling effort homed in on the top corner.
Villas-Boas had clearly seen enough by half-time, and duly took off the ineffective Fernando Torres at the break for returning Ivory Coast striker Didier Drogba.
Chelsea's higher-tempo start to the second half paid off in the 62nd minute, when Branislav Ivanovic sent in a teasing cross from the right which an unmarked Sturridge met with a glancing header.
But while Chelsea continued to dominate both territory and possession thereafter they struggled to create clear chances, and not even the late introduction of Frank Lampard for Mata could break the deadlock.