The Blues' 7-4 victory over the Royals was the most number of goals scored in a top-flight fixture - a record that still remains intact.
Benjani was the star for then-Pompey boss Harry Redknapp's side on 29 September 2007.
The Zimbabwean struck a hat-trick on an afternoon those in attendance will never forget.
Remarkably, the score was 2-1 at half time after Benjani's double inside 37 minutes and Stephen Hunt's strike minutes before the interval.
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But there would be a further eight goals netted after the restart, on what turned out to be a record-breaking afternoon.
Former Pompey striker Dave Kitson made it 2-2 on 48 minutes following an error from goalkeeper David James.
Hermann Hreidarsson restored the Blues’ advantage on 55 minutes before James saved a Nicky Shorey penalty.
Benjani completed his hat-trick on 70 minutes, with Niko Kranjcar firing Pompey 5-2 in front five minutes later.
Shane Long reduced the arrears 11 minutes from time but Sean Davis restored Redknapp's troops' three-goal advantage two minutes later.
But there was still time for Sulley Muntari and Shorey to net in stoppage-time as Premier League history was created.
Speaking after the record-breaking fixture, Pompey coach at the time Joe Jordan said: 'The first half was probably our best 45 minutes this season, but to come in having conceded in the last minute of the half allowed them back in.
'Even at 2-2 I don't think anyone expected the score to be exaggerated to 7-4, but overall I think the best team won.
'People say we only play one up front but we proved that it's really three and no-one deserves a hat-trick more than Benji.'
To this day, the 11 goals scored in the fixture remains a Premier League record.
Five matches, Arsenal 7-3 Newcastle (December 2012), Tottenham 9-1 Wigan (November 2009), Tottenham 6-4 Reading (December 2007), Manchester United 8-2 Arsenal (August 2011), West Brom 5-5 Manchester United (May 2013), have all managed ten goals since Pompey and Reading made history.