Chelsea held by second tier Birmingham in Cup

* Sturridge equalises as Chelsea come from behind to draw

* Villas-Boas says he has owner’s “unconditional” support (Adds details and quotes)

LONDON, Feb 18 (Reuters) - Daniel Sturridge headed in the equaliser as Chelsea drew 1-1 with Birmingham City on Saturday to force a replay of their FA Cup fifth-round encounter after a performance that did nothing to alleviate the pressure on manager Andre Villas-Boas.

The well-organised Championship (second division) visitors had taken a 20th-minute lead through Danny Murphy before their top-flight opponents pulled one back with Sturridge’s goal midway through the second half.

Chelsea had squandered an earlier chance to level straight after Murphy’s opener when Juan Mata’s penalty was well saved by diving Birmingham keeper Colin Doyle and home fans expressed their unhappiness by chanting ex-manager Jose Mourinho’s name.

“It is a poor result of course,” Villas-Boas, who said he had the “unconditional” support of owner Roman Abramovich, told ESPN.

“But it was an excellent performance in the second half compared to the first…1-1 is not what we expected but it gives another chance at Birmingham to try to reverse things.”

Later in the day, Arsenal travel to Sunderland in an all-top-flight encounter, while fellow Premier League clubs Everton, Bolton Wanderers and Norwich City face Championship sides Blackpool, Millwall and Leicester City respectively.

Favourites Tottenham Hotspur travel to League One (third tier) Stevenage on Sunday.

Chelsea went into the match at Stamford Bridge on the back of a poor run of form in the league, where they have won just two of their last 10 games, and they came out of it to a chorus of boos from home fans.

They looked second best against a spirited Birmingham right from the start and were punished when Murphy thumped in the ball from a Nathan Redmond corner.

MOURINHO CALLS

Chelsea, who have won three of the last five FA Cups, should have levelled less than two minutes later when Ramires was brought down by a clumsy challenge from Wade Elliott and referee Martin Atkinson pointed to the spot.

Mata stepped up to take the penalty but his low effort was palmed away on to the post by the excellent Doyle.

The Birmingham keeper was the hero again when he tipped over David Luiz’s well struck free kick 10 minutes later, while Sturridge went just over the bar with a long-range drive shortly before the break.

The “Jose Mourinho” chants rang out as the Real Madrid boss found himself in demand at yet another of his former clubs after Inter Milan fans also called for the Portuguese to come to their rescue following another defeat in Serie A on Friday.

The calls subsided when Sturridge headed in from Branislav Ivanovic’s good cross from the right on 62 minutes but the boos erupted when the final whistle went without Chelsea having found a winner.

Villas-Boas, appointed in the close season to replace the sacked Carlo Ancelotti who led the club to an FA Cup and Premier League double in 2010, had said this week there was no panic at the club and that his position was not under threat.

Owner Abramovich has shown no mercy with managers who have failed to deliver silverware and while the team are still in the running for the Champions League, the trophy he covets the most, this draw may not sit well with the Russian.