NIGERIAN striker Yakubu tore Middlesbrough to shreds to finish above Saints favourite James Beattie as the south coast's top scorer in the Premiership.
Beattie finished with 17 league and cup goals, but Yakubu closed on 19 after a four-goal final-day burst against a dismal Middlesbrough side.
Yakubu scored clinically from an Eyal Berkovic pass early on.
He added a penalty soon afterwards when the often maniacal Danny Mills hauled him down.
And he completed his hat-trick just after the half-hour following Ugo Ehiogu's blunder.
Yakubu got a fourth - after Teddy Sheringham came on as a substitute to make it 4-1 with a tap-in - eight minutes from time.
He then missed a sitter and what a relief that turned out for boss Harry Redknapp, who admitted: "I had forgotten at the start of the year I had promised him £20,000 out of my own pocket if he scored 20 goals. If I had remembered that I would have substituted him."
Yakubu, who has hit 11 goals in the last 10 games - a run which started with his winner against Saints in March at Fratton Park - said: "I'm happy enough that I'm scoring and hope I can do the same here next season.
"I certainly want to be here and the only reason I am already is probably Harry.
"He could have dropped me a few times when I wasn't scoring but he kept me in the team and showed faith in me. That is what you need. Now I feel like I will score in every game."
Portsmouth striker Svetoslav Todorov faces another threat to his career and more major surgery on his damaged knee after missing most of the season.
Bulgarian marksman Todorov had an operation in America in September after a freak accident in training just three days before the start of the season.
He attempted a comeback in March but managed only a handful of reserve games and 45 minutes of a 3-0 Premiership defeat at Liverpool before severe bone-bruising was diagnosed.
The problem, however, has become much worse.
Redknapp, meanwhile, wants to sign Newcastle striker Lomana LuaLua on a permanent deal.
He also wants to extend the loan for another season on Chelsea's midfielder Alexei Smertin, who cost the London club £3.4million from Bordeaux but has never played for them.
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