Jermain Defoe scored twice in the first 10 minutes to send Portsmouth on their way to a 4-2 win over Birmingham at Fratton Park.

Birmingham hit back with goals from Fabrice Muamba and Sebastian Larsson to leave the scores at 2-2 at the interval before Hermann Hreidarsson, four minutes after the restart, and Nwankwo Kanu, in the second minute of added time, secured the win for Pompey.

Portsmouth got off to the perfect start when Milan Baros got the better of Liam Ridgewell on the right of the box and earning his side a penalty when David Murphy was judged to have handled the ball.

Defoe calmly stepped up to send the ball into the bottom right corner of the net and just three minutes later he had a second as Birmingham were caught napping at the back.

The diminutive former Tottenham striker found himself in the right place at the right time when Baros's shot was deflected by visiting keeper Maik Taylor into his path after Sulley Muntari had also seen his shot parried.

Blues boss Alex McLeish only had to wait 60 seconds though before his side made their mark on the match with Birmingham earning themselves a corner from the re-start.

Larsson whipped his ball in towards the penalty spot, Ridgewell headed on towards the far post where Muamba, having made a great run to appear from nowhere, was on hand to deflect the ball into the back of the net.

After three goals in five minutes, Portsmouth had to wait until the 33rd minute before fashioning another real chance on goal.

Muntari's free kick, after Gary McSheffrey brought down Baros, was allowed to go untouched and almost curled into the left corner of the net before Taylor managed to scramble across and turn the ball behind for a corner.

It was Birmingham, however, who went in for half-time with smiles on their faces after Larsson had levelled with a brilliant free-kick thumped into the top left corner of the net after Mikael Forsell had made the most of Glen Johnson's tackle.

Portsmouth came out for the restart firing on all cylinders and Hreidarsson put the hosts back in front when he tapped home from six yards after Muntari's free-kick came off Ridgewell's head and into the path of the Icelander.

Birmingham had a chance to equalise in the 77th minute when Larsson produced a great chipped cross for substitute Cameron Jerome, whose header towards the near post almost caught David James napping.

But the England keeper was quickly across to his right and managed to tip the ball around the post.

Muntari then tried his luck from 25 yards, after Kanu had laid the ball back, and watched as his shot just went over the crossbar as a worried Taylor scampered across to cover.

But it was Kanu who eventually gave the hosts the breathing space when he produced an acrobatic header in the second minute of extra time to secure the win.

Pedro Mendes found himself in acres of space on the right wing before picking out Kanu at the far post and the Nigerian completed the scoring that saw his club move up to seventh in the Premier League.

Pippa Davis / Eurosport