Grainger curled home an 11th-minute free-kick from 25 yards before Johnson scampered away after 71 minutes to seal the win and leave the Birmingham fans chanting 'Bring on Liverpool'.

It was a thoroughly professional performance by City against a Preston side who came into the game on the back of three wins.

In fact it was Preston who started the game brighter despite boss David Moyes having to dispense with his three-man strike force due to leading scorer Jon Macken's late withdrawal with illness.

And after six minutes they could have taken the lead when good interplay by Paul McKenna and Colin Murdock found Mark Rankine in space in the box.

But the former Wolves man curled a shot from 12 yards wide of Ian Bennett's far post.

And after 11 minutes Rankine added to the Preston fans' frustration at his failure to score by giving away the free-kick that led to Birmingham's opener.

The midfielder hacked down Andrew Johnson and with Preston goalkeeper Teuvo Moilanen seemingly out of position Grainger picked his spot to curl the ball in from 20 yards.

The goal spurred North End into life and after Bryan Hughes had hacked away a David Healy knock down as Jackson looked set to pounce, Rankine saw hispile-driving shot from the resulting corner blocked by a posse of Birmingham defenders.

But Preston were grateful to Moilanen after 19 minutes when he produced an incredible save to deny Marcelo.

Murdock gave the ball away to Johnson wide on the right and the young striker, in for hamstring victim Geoff Horsfield, fed Marcelo eight yards from goal but Moilanen somehow managed to turn the Portuguese star's goalbound effort round the post.

Moilanen was in action again after 26 minutes when he dived smartly to his left to stop a Curtis Woodhouse shot.

Preston ended the half on the attack and Bennett had to tip a McBride header over the bar as Preston pushed for the equaliser.

But Birmingham nearly doubled their lead four minutes into the second half when Hughes jinked in from the left and curled his shot against the post with Moilanen beaten.

City were looking comfortable and playing controlled football but after 55 minutes that nearly went to waste as Preston almost scored when Rob Edwards crossed in from the right and Lee Cartwright, racing in at the back post, saw his goalbound shot deflected for a corner.

Birmingham were soon back on the attack and Jon McCarthy fired a shot just over the bar after a good knock down by Marcelo.

And after 71 minutes Birmingham got their second goal. Preston lost the ball in midfield and Johnson outpaced Edwards to McKenna's pass before cutting inside and slotting the ball under Moilanen.

Preston continued to battle and went close through Healy and Michael Jackson before substitute Brian Barry-Murphy should have scored after 86 minutes.