The game, after being on a slow cooker, sizzled into life to a degree on ten minutes when David James was unable to gather a deflected cross and Pascal Chimbonda attempted to inject some further mayhem, before Robbie Keane tested James down to his right.
Tom Huddlestone then stretched the veteran keeper with a free-kick that he was able to pluck out from underneath the crossbar. Paul Robinson then eclipsed his work with a brilliant tip over from a Sean Davis chip that was sailing in.
A dipping volley from Chimbonda was then inches from opening our account for the afternoon. Berbatov had a goal ruled on 27 minutes after a precise ball through from Keane, the striker's neat footwork easing past the attentions of James. Moments later Michael Dawson rattled the crossbar after seizing on the loose ball from a corner.
Berbatov should have scored ten minutes before the break when Lennon provided the ammunition inside the area, but his shot was floated too high.
There was almost as much variety in the weather as in the game with assorted elements to contend with during the first half, one which was nearly illuminated by Huddlestone connecting with a headed clearance full on the volley and his shot arrowed just over.
The wind was again gathering speed at the beginning the second half - swiftly followed by the rain - and playing conditions could not have been straightforward. A Lennon shot that squirted just wide was the first significant action of the half - apart from the snow.
With quality goalmouth action at a premium, despite plenty of endeavour, we waited for the spark to lift this contest. Juande Ramos responded with a double change - Darren Bent and Jamie O'Hara, for Lennon and Dawson, with Didier Zokora again switching to the back.
It remained stalemate all the way, but Pompey had the chance to steal when a long ball into our area was reacted to first by Kanu, who got in front of Robinson and looked set to finish until Zokora scooped the ball away from danger with a last-ditch manoeuvre.
The deadlock was broken in the 80th minute after both Steed Malbranque and Berbatov had a go in the area, Berbatov shooting downwards allowing Bent to get on the end of it and nod past James.
A minute later the other substitute delivered after Bent charged down the left and slipped the ball inside to where O'Hara was waiting to slot home.
It would be fair to suspect that the substitutions changed the game...
Darren Bent scored the 100th goal at the Lane this season in what was the 250th senior appearance of his career.The striker came on and brightened up an encounter that was labouring somewhat in weather conditions that lurched from one extreme to the other. The introduction of Bent and Jamie O'Hara did the trick as we entered the final ten minutes and there was no Pompey response.