Birmingham 1 Chelsea 0

A first-half goal by Lee Bowyer saw relegation-threatened Birmingham beat league leaders Chelsea.

But the result owed as much to heroic defending and an outstanding performance by Blues goalkeeper Ben Foster, as the champions bombarded the home goal at St Andrews.

Alex McLeish's side held on under intense pressure to record a memorable win – and condemn Chelsea to their first back-to-back league defeats in 165 games, a run dating back to the tail end of their 2005/06 title-winning season.

For the second week running, boss McLeish again opted for the more attacking 4-4-2 formation against one of the Premier League's big boys, instead of the expected 4-5-1.

Predictably it was the visitors who started most brightly. Chelsea showing their class in just the sixth minute when Salomon Kalou split the Blues defence and Foster got down low to smother Didier Drogba's corner-bound shot.

Drogba nodded just over eight minutes later, from Nicolas Anelka's teasing cross, with Blues beginning to look nervous as the league leaders began to flex their muscles.

But the home side's tentative start was transformed in the 17th minute, when Bowyer superbly slotted home the opening goal from Cameron Jerome's nod down.

It was a slick move which also owed much to Sebastian Larsson, for the initial cross, and Barry Ferguson, who attacked the loose ball to set up the move.

From that moment on until half time, the game became the Ben Foster show as the goalkeeper made world-class save after world-class save to deny the visitors.

Foster did well to hold onto Drogba's fizzing low drive and then produced the save of the game, by somehow pushing the striker's close range header round the post from barely eight yards out.

Ashley Cole then found himself one on one with the goalkeeper from Kalou's through-ball but again his effort was blocked by Foster, before Branislav Ivanovic headed powerfully over from the corner.

Anelka forced another smart save before half time, while Alex flashed an unmarked header wide as Chelsea's frustrations grew.

And even when Drogba managed to beat the keeper, six minutes before the break, his looping header cannoned back off the post.

Blues managed to frustrate the visitors for the first 15 minutes of the second half, without much trouble, but Larsson had to show bravery to block Ramires' volley from a corner kick.

Johnson then produced a superb tackle on the same player inside the box after the Brazilian had burst through.

But the defender picked up a knock on the shin for his troubles, although Blues were looking as comfortable as a relegation-threatened team could against the league leaders, albeit without much possession.

Chelsea manager Carlo Ancelotti swapped Paulo Ferreira for Jose Bosingwa with left 20 minutes remaining and the Portugese winger flashed a shot just wide soon after.

Drogba then fired a free kick straight at Foster and Kalou drifted a diving header just wide from Anelka's inviting cross.

In search of a goal, on came Daniel Sturridge to replace ineffective Ramires for the final 18 minutes.

Foster pulled off another superb save with 17 minutes remaining, tackling Kalou with his feet and then punching the ball from his feet as the ball ran free.

Blues were now constantly being bombarded as Chelsea probed and pressed for an equaliser, but some heroic blocks and headers from the back four in particular.

Stephen Carr, Johnson and Ferguson all made brave blocks but Blues luck held, as Foster saved Branislav Ivanovic's close range header with 14 minutes left, before saw the rebound smashed over the bar by the same player.

Liam Ridgewell and Keith Fahey were both booked late on for clumsy challenges as the home side's frustration grew, with wave after wave of Chelsea attack coming forward.

But Blues held firm for a deserved and memorable win, which pulls them clear of the relegation zone and into mid-table.