Striker Jason Roberts grabbed the all-important goal that took West Brom up to third spot in the table as he marked boss Gary Megson's 100th game in charge with a deserved victory.

Roberts, Albion's most expensive signing at £2million, settled the Midlands derby when he found the target in the 43rd minute at The Hawthorns.

The hitman collected a marvellous crossfield ball from Adam Chambers before slotting a terrific angled drive past keeper Ian Bennett and into the far corner of the City net.

Megson's high-fliers have now been forced to take defeat just once in their last nine outings while Birmingham are still chasing their first success in 2002.

But Albion's victory over their near neighbours - it was the 11th time this term they have won 1-0 - should have been far more convincing.

Roberts, who has now grabbed three goals in eight games since recovering from a broken foot, wasted a great chance in the 17th minute after he took the ball off City defender Jeff Kenna.

The striker had just Bennett to beat but the keeper dived to bravely smother the shot from Roberts.

Then, in the 51st minute Roberts was in another one-on-one with Bennett and the keeper denied him for a second time as he dived to steal the ball.

It was always Megson's promotion chasers who held the edge against a City line-up badly hit by suspension and injury problems.

Slovakian international Igor Balis lashed an early shot just over the woodwork while Larus Sigurdsson powered his header wide of the far post from a good position.

Neil Clement also fired in a cracking left-footer for Albion in the 40th minute only to see the ball fly just inches wide of the City goal-mouth.

The best chance from Blues in the first half came on the half hour when Andrew Johnson blasted in a shot that flew straight to keeper Russell Hoult.

After the break, Hoult joined the action when he did well to punch away a Michael Johnson header to a corner from Martin Grainger.

Albion were soon holding the initiative again and Roberts squandered another great chance of doubling his advantage when he was denied yet again by Bennett with the City defence caught flat footed.

Teams

West Brom: Hoult, Gilchrist, Moore, Sigurdsson, Clement, McInnes, Johnson, Balis (Lyttle 83), Adam Chambers (Fox 54), Roberts, Dichio (Dobie 54).

Subs Not Used: Jensen, Taylor.

Booked: Sigurdsson.

Goals: Roberts 43.

Birmingham: Bennett, Kenna (Marcelo 81), Purse, Michael Johnson, Grainger, Eaden, Hughes, Carter, Lazaridis, Andrew Johnson, Furlong (Mooney 63).

Subs Not Used: Vaesen, McCarthy, Burrows.

Booked: Mooney.

Att: 25,266

Ref: P Allcock (Surrey).