Lomana LuaLua made a dramatic impact by scoring the winner at Charlton to put Portsmouth top of the Premiership.
LuaLua made a dramatic impact
The DR Congo striker was called off the bench by boss Harry Redknapp and responded with a raking drive which beat keeper Scott Carson's dive.
Charlton striker Marcus Bent looped a header on to the Portsmouth crossbar in the opening minute.
But Pompey's defence remained intact for the fifth successive game for their best start in the Premiership.
Injuries forced Charlton boss Iain Dowie to field an attacking 4-3-3 line-up and it almost paid instant dividends.
Dennis Rommedahl drifted a cross to the far post where Marcus Bent headed the ball against the bar and Darren Bent hammered the rebound against the outside of a post from a tight angle.
Talal El Karkouri nicked Gary O'Neil's cross off Kanu's head at the other end and as the game developed into an open affair the Moroccan defender got forward to power a header inches wide from a corner.
Kanu had a shot pushed around the post by Carson and then headed wide Glen Johnson's inviting far-post cross when he should have put Pompey ahead.
Luke Young's wayward backpass from the halfway line conceded a needless corner and he almost paid dearly as Sol Campbell rose to power a header just wide.
Charlton's formation left them under-manned in midfield and Pompey's Sean Davis drifted into the vacant space to draw another good save from Carson.
Luke Young gives chase to Portsmouth's Gary O'Neil
Addicks' boss Dowie addressed the problem of his team's shortcomings in midfield at half-time by introducing Jon Fortune for Marcus Bent and reverting to a 4-4-2 formation.
It gave Charlton more control in midfield and allowed them to use Rommedahl's pace out wide as they tried to stretch a Pompey defence unbreached in four matches.
Rommedahl came close to breaking the deadlock when Kanu's defensive header dropped for the Dane to bullet a searing volley inches wide of David James' left-hand post.
Charlton's second-half dominance prompted Redknapp into a change and his introduction of LuaLua proved crucial.
The 25-year-old striker collected a loose ball and although his shot took a slight deflection off Amady Faye it still had enough power to beat Carson's despairing outstretched right arm.
Charlton boss Iain Dowie:
"They had one shot on target in the second half and so it's disappointing to lose.
"We did not disturb their back four and our basic ball retention was not good enough.
"We failed to pass with any intent but we now have to crack on and show our endeavour.
"There was a lack of desire and we have to put that right."
Portsmouth boss Harry Redknapp:
"We've carried on from where we left off last season when we took 20 points from our last 10 games.
"We have been brilliant so far this season. We are trying to finish above our highest previous finish in the Premiership which is 13th.
"We've had a good start but we're not getting carried away."
Charlton: Carson, Kishishev (Lisbie 80), El Karkouri, Faye, Young, Rommedahl, Pouso (Holland 57), Ambrose, Marcus Bent (Fortune 45), Darren Bent, Hasselbaink.
Subs Not Used: Myhre, Ashton.
Portsmouth: James, Johnson, Campbell, Primus, Stefanovic, O'Neil (Thompson 89), Davis, Pedro Mendes, Taylor, Kanu, Mwaruwari (LuaLua 64).
Subs Not Used: Kiely, Pamarot, Koroman.
Booked: O'Neil, Kanu.
Goals: LuaLua 74.
Referee: P Dowd (Staffordshire).