Birmingham piled more pressure on Fulham's under-fire manager Chris Coleman as they cruised to a fourth straight win.
Coleman's position was weakened further by a defeat which keeps the Londoners in the thick of the relegation battle at the foot of the Barclays Premiership.
Fulham were booed off the pitch for the second time at the end of an encounter that could well have serious repercussions for Coleman's hopes of staying in charge at Craven Cottage.
Robbie Savage add the decisive third goal for Steve Bruce's impressive side in the 52nd minute and City were well worth their victory.
After a poor opening period, Birmingham took the lead through former England international Emile Heskey but Sylvain Legwinkski equalised eight minutes later.
However, five minutes before the break, Darren Carter restored City's advantage to spark a furious volley of abuse at Coleman and his players as they left the pitch at the break and at full-time.
The game had started promisingly enough for Fulham but often found themselves out-muscled by the Birmingham midfield in which Carter and Savage patrolled with vigour.
The blustery conditions also made life difficult for both sides and numerous passes fell victim to poor judgement and accuracy.
The opening quarter was tepid in the extreme for a game that both sides were desperate to win and neither goalkeeper was called upon to excel themselves.
It was Birmingham's Heskey who brought the game to life in the 25th minute with a quality goal. Savage won the loose ball unchallenged in the midfield and slipped a simple pass to Clinton Morrison on the edge of the penalty area.
The quick-thinking striker then exchanged passes with Heskey before the former Liverpool man unleashed a rising drive into the roof of the net beyond the outstretched van der Sar.
Fulham's fans showed their displeasure with the performance by booing Legwinski every time he touched the ball but in the 33rd minute, their jeers turned to cheers when the midfielder hauled Fulham level. Papa Bouba Diop's shot on the edge of the area was deflected into the path of Radzinski and his cross was despatched into the roof of the net by Legwinski.
The goal brought a dreadful encounter to life and a minute later van der Sar was forced to pull off a superb one-handed save to prevent Carter restoring Birmingham's advantage.
Seconds after van der Sar's save, City 'keeper Taylor had to be at his best to
deny Radzinski after Cole had put him in the clear.
But Carter restored Birmingham's lead in the 40th minute when Savage's cross
was knocked-down by Heskey and the unmarked City midfielder made no mistake from
the angle of the six-yard box.
City almost made it three minutes later but van der Sar managed to hold to
Morrison's shot and the Fulham fans booed their side off at half-time.
A brilliant save from former Fulham goalkeeper Taylor denied Cole an equaliser
just one minute after the restart.
Cole chested down Radzinski's cross and turned to fire a low, angled drive
towards the bottom corner but Taylor was equal to it.
Coleman had clearly read the riot act to his side during the half-time
interval and had also replaced central defender Ian Pearce with Zesh Rehman.
The Fulham fans were still unhappy with elements of their display in the
second period. City looked good value for their lead and pressed forward in
search of what would almost certainly be the decisive goal of the encounter.
That duly arrived in the 52nd minute when Savage scored a fine goal to make it
3-1. Heskey laid the ball back to the Wales international on the left angle of
the penalty area and Savage flicked the ball up with his right-foot before
despatching an admirable volley into the roof of the net with his left. The goal
understandably sparked another chorus of boos from the home fans who were
incensed with the lack of desire from their side.
In the 56th minute Coleman made a double substitution in an effort to salvage
something from the game - Elvis Hammond and Steed Malbranque replacing the
ineffective Brian McBride and Collins John.
It made little difference to a Fulham attack that was marshalled superbly by
Matthew Upson and Kenny Cunningham.
With 10 minutes remaining Hammond got free of his marker to head the ball
towards the City goal but once again Taylor proved to be a thorn in the side of
his old club by making a fine stop.
Radzinski scored a late consolation effort for the home side but it wasn't
enough to stop some of the home fans calling for the head of Coleman as he left
the pitch.
Teams
Fulham Van der Sar, Volz, Knight, Pearce (Rehman 45),
Bocanegra, John (Hammond 57), Legwinski, Diop, Radzinski, Cole,
McBride (Malbranque 56).
Subs Not Used: Pembridge, Crossley.
Booked: Rehman.
Goals: Legwinski 34, Radzinski 90.
Birmingham Maik Taylor, Tebily, Cunningham, Upson, Melchiot,
Johnson, Carter, Savage (Anderton 86), Clapham,
Heskey (Gray 75), Morrison (Clemence 82).
Subs Not Used: Martin Taylor, Vaesen.
Goals: Heskey 25, Carter 41, Savage 53.
Att: 18,706
Ref: M Clattenburg (Co Durham).