Portsmouth blew the Premiership title race wide open with a shock victory over leaders Manchester United.
Matt Taylor celebrates scoring Pompey's opener
Pompey went ahead when Edwin van der Sar could only parry Benjani's shot and Matt Taylor followed up to score.
United pushed forward but David James denied Cristiano Ronaldo and Ryan Giggs before Rio Ferdinand put Taylor's pass into his own net to put Pompey 2-0 up.
John O'Shea replied from close range but James made sure of victory with a superb last-gasp save from Alan Smith.
Having seen Chelsea beat Tottenham earlier in the day and reduce their lead to three points, the pressure was on United to continue their impressive run of seven straight league victories.
But Pompey had other ideas and the home side's tactic of hustling United's defence paid off in the early stages as Harry Redknapp's men enjoyed all the initial pressure.
Van der Sar only had to deal with one effort on goal - a header by Kanu - but it was still a warning to United and they finally woke from their slumbers.
Ronaldo smashed a long-range free-kick wide of James' goal and was close to finding the target again soon after a typically mazy run.
It seemed United were gradually taking control but Pompey kept working hard even when they did not have the ball and their industry paid off on the half-hour.
Kieran Richardson was caught in possession outside the box by Benjani, who fired in a dipping shot that Van der Sar could only palm into the path of Taylor, who gratefully slotted home.
United responded well and Michael Carrick and Wayne Rooney fired wide before Darren Fletcher forced James into his first save of the match.
But Pompey were still dangerous themselves and almost increased their lead before the break.
Linvoy Primus headed over from a Gary O'Neil corner, then Van der Sar had to save smartly after he reacted first to Kanu's flick-on.
The second half was always going to be about whether United could find an equaliser - and they surely would have done if not for the form of James.
He denied Ronaldo and Ole Gunnar Solskjaer in quick succession before Lauren cleared the ball off the line.
James then somehow tipped over a powerful Giggs shot and caught a Wes Brown header as United piled on the pressure.
Portsmouth were not finished yet, however, and only a brilliant save by Van der Sar denied Sean Davis after he met Taylor's cross.
United kept coming forward but Sir Alex Ferguson's side were left stunned when Ferdinand turned the ball into his own net in the final minute.
Taylor's hopeful pass was meant for Lomano LuaLua but instead the England defender diverted it past Van der Sar on the edge of the box and the ball trundled over the line.
That did not deter United and O'Shea gave them hope in injury time when he tucked away the rebound after James fumbled Solskjaer's shot.
There was still time for substitute Smith to find an opening but James made a final brilliant save to deny him as Pompey held on for a famous victory.
Portsmouth manager Harry Redknapp:
"We told the players on Friday that the only way we were going to win was if we all grafted. The players worked their socks off.
"We got in United's faces whenever we could and made it difficult for them.
"We decided to press them all over the park and not sit back. We met them halfway up the park and it worked."
Manchester United manager Sir Alex Ferguson felt his side's midweek exploits in the Champions League caught up with them:
"An away game after a European tie is always difficult but playing with 10 men for so long in Rome told here.
"We had some decent chances but their keeper made some excellent saves.
"These things happen. It has come at a bad time but we have showed character all season and must do so again now."
Portsmouth: James, Lauren, Primus, Stefanovic, Traore, O'Neil, Davis, Hughes, Taylor, Mwaruwari (LuaLua 67), Kanu (Kranjcar 81).
Subs Not Used: Ashdown, Pamarot, Todorov.
Booked: Lauren, James, O'Neil.
Goals: Taylor 30, Ferdinand 89 og.
Man Utd: Van der Sar, O'Shea, Ferdinand, Brown, Heinze, Fletcher (Solskjaer 59), Scholes, Carrick (Smith 77), Richardson (Giggs 46), Rooney, Ronaldo.
Subs Not Used: Kuszczak, Evra.
Goals: O'Shea 90.
Ref: M Clattenburg (Co Durham).