Two inspirational moments of skill from Emile Heskey kept Leicester's twin Wembley assault on track as they emerged victorious from their Midlands derby with Birmingham.

The England Under-21 international had few chances of his own but was alert enough to play a back-heeled one-two with Frank Sinclair after 21 minutes which left the crowd gasping.

Sinclair seized on Peter Ndlovu's wasted pass, raced at the Blues defence, then smashed home the opener from Heskey's return.

Then, at the start of the second half, Heskey repeated the dose to set up strike partner Tony Cottee and end Birmingham's brief hopes of causing an upset.

Earlier, in a six-minute, two-goal salvo, Rob Ullathorne blasted home the rebound from his own initial shot as Leicester's full-backs proved a change in formation was no barrier to their attacking prowess.

Sharing six losing finals and no winning ones between them, neither side went into the game with a particularly impressive recent FA Cup pedigree.

Leicester had failed to progress beyond the opening stage for nine of the past 13 seasons, while Birmingham had done so on just two of the last 10 occasions.

A rib injury prevented veteran centre half Steve Walsh making his third game in a week, giving Gerry Taggart a place at the heart of the Leicester defence.

The knee ligament injury Robbie Savage picked up against Blackburn on Monday saw Stuart Campbell make his first start since September.

Martin O'Neill abandoned his usual wing-back formation in favour of pushing Steve Guppy into a more forward role down the left and the Worthington Cup semi-finalists had an early claim for a penalty.

Tony Cottee felt he should have had a spot-kick when he was shoved over in the area by Gary Rowett with the game barely 120 seconds old, but referee Uriah Rennie was unsighted.

Cottee wasted the best early chance when he flashed a header wide of the post after Heskey had delivered the perfect cross.

Leicester's double strike midway through the half appeared to put the Premiership side into cruise control but Steve Robinson's first of the season, a first-time half-volley from Paul Furlong's cushion header which crashed in off the bar, gave Birmingham hope at the break.

After half-time, Heskey continued to cause problems in the air and on the ground, and the burly striker's willingness to work the flanks was admirable.

He screwed a shot wide before heading on to set up a wasted half-chance for Cottee but the back-heel Birmingham had seen more than enough of already, revisited them like the flash of lightning that should never strike twice.

This time, it was Neil Lennon's pass which found Heskey with his back to goal and Cottee's charge into the box, but it was the man mountain with the touch of a ballet dancer who brought the crowd to their feet.

Birmingham briefly rallied, Furlong's snap shot flying marginally over before Gerry Taggart matched the Blues front man shoulder to shoulder in the battle to reach Ndlovu's near post cross.

It proved to be Furlong's last contribution but at the other end, Heskey was still intent on making his mark, Robinson clearing a downward header off the line.

Guppy reminded the bulging Filbert Street terraces that he is supposed to be the attacking wideman in these parts, with a goal that almost eclipsed Heskey's earlier assisted contribution.

Picking the ball up on the left, Guppy strode forward, cut across the Birmingham defence and then unleashed a curling right-foot strike which nestled into Poole's goal in much the same place as Cottee's earlier effort had done.

Dele Adebola pulled one back in the last minute for Birmingham but the chasm in class between the Premiership and Nationwide League had been comprehensively maintained.

Teams:

Leicester: Keller, Sinclair, Ullathorne, Elliott, Taggart, Izzet (Parker 85), Lennon (Zagorakis 85), Campbell, Guppy, Cottee (Marshall 74), Heskey.

Subs Not Used: Arphexad, Fenton.

Booked: Cottee, Sinclair.

Goals: Sinclair 20, Ullathorne 26, Cottee 51, Guppy 70.

Birmingham: Poole, Rowett, Marsh (Grainger 45), Robinson, Ablett, Johnson, McCarthy (Hughes 77), Adebola, Furlong (Forster 63), O'Connor, Ndlovu.

Subs Not Used: Bennett, Purse.

Goals: Robinson 35, Adebola 89.

Att: 19,846

Ref: U Rennie (Sheffield).