The visitors crucially got themselves into a two goal lead by the half hour mark and that advantage proved to be too much for the Royals to come back from over the remaining hour of the game.
What was remarkable was this game brought six goals between two sides who had only conceded 12 times in 19 league games between them before this encounter.
Just as remarkable was both sides producing an entertaining, attacking game in awful conditions, with torrential downpours for long periods during the 90 minutes.
Andover made a quick start to the game and on five minutes a throw in from the right picked out Lewis Williams but he dragged his shot wide from 20 yards out.
Two minutes later a free kick was hit deep into the Portchester box and Shane Lock’s high looping header almost caught Steven Mowthorpe out but the keeper got back quickly enough to push the ball away as it dropped towards the net.
However, Andover took the lead when the ball was hit low across the face of goal and Scott Hassell appeared to get the final touch to guide the ball into the net - there was more than a hint of offside to the goal but no flag came from the linesman.
On 13 minutes the visitors went close to extending their lead when the ball was worked forwards through the midfield and Mowthorpe had to push Williams’ shot from the edge of the box away from his goal.
Portchester’s defence then gave the ball away inside their own penalty area and were relieved when Issiaga Kaba blasted his shot well over the goal.
On 17 minutes the Royals came alive at the other end of the pitch when a pass from midfield found Ryan Pennery, who took the ball into the left side of the penalty area but his shot was blocked. From the corner Ryan Wilkins fired a shot on goal but it was cleared off the line.
On 24 minutes keeper Matt Fredericks had to push Charlie Williamson’s free kick from the left side of the box away for a corner to prevent it from going in.
But just as Portchester looked to be edging their way back into the game the visitors scored a second goal on 30 minutes when Kaba picked up a clearance on the edge of the box and fired his shot into the net.
A measure of how the Royals’ luck was going in this game came a minute later when they could have hit back immediately but Connor Duffin’s (pictured above) downward header inside the six yard box bounced up over the crossbar.
In the next attack Lee Wort was sent clear in space down the right wing but his cross bounced off the crossbar and away to safety.
The Royals did managed to pull a goal back on the stroke of half time when a corner from the left was cleared to the edge of the box and Duffin riffled his shot into the net.
Unfortunately the home side slipped from the foothold in the game their goal gave them when they conceded again five minutes into the second half. Matt Scott’s header from a corner was initially blocked but he managed to force the rebound home from close range.
Wort then had two chances to try and cut Andover's two-goal advantage. The first came from a ball in from the left but his shot rolled through to Fredericks and then Williamson crossed low into the box from the right but Wort’s shot from six yards out was blocked by the keeper’s foot.
On 64 minutes good play through midfield saw the ball worked to Pennery on the edge of the box but he was denied by another fine save from Fredericks.
The Royals did get their second goal a minute later when the ball was crossed into the six yard box from the right and Pennery was there to blast the ball into the net.
As the home side pushed for an equaliser this left them vulnerable to counter attacks from the visitors and on 68 minutes Claudio Herbert got clear but Mowthorpe got down quickly to block the ball at the striker’s feet.
Wilkins flicked his header wide from a cross from the left before Wort had the best chance of getting an equaliser with a minute of normal time left on the clock. The ball came into the box from the left and Wort held off his marker before trying to hit the ball towards goal but his effort was cleared away as it looped up towards the net.
In injury time a long ball forward from Mowthorpe found Pennery but he dragged his shot well wide of the far post before substitute Jake Rawkins was sent racing clear for the visitors and he smashed his shot into the net from 25 yards out.