The heavy downpour at the start had restricted the flow of the game as players from both teams were often caught in no-man's land with the rain-soaked pitch and had difficulties controlling the ball and making decent passes.
Despite the awful condition, it was a tightly contested match and both team played aggressively and the visitors were certainly the better team in terms of ball possession.
The winning goal came in the first period of the match when a lapse of concentration by the Sabah defenders who were so organised at the start allowed the Bruneians to convert their first real opening opportunity from close range.
Any chance of a revival for the home team was dashed at the restart as they were reduced to 10-man after Mohd Ikhmal Akid Bahari was shown the exit for his second booking of the match.
Head coach Justin Ganai , who is preparing the team for the Inter-City Football Champions tournament in Kuching in December was upbeat despite the loss and praised his boys for their fighting spirit.
"It was never going to be easy to play under such condition.
We couldn't play our usual game, but we must admit that we were up against a national team and for our boys who are all under 21 years of age to come away with only a 1-0 loss is no shame."
He said it was a very good all round performance from the boys especially the defence apart from the goal conceded.
"They were very solid at the back and displayed very good character and discipline to thwart any Bruneian attempts at goal especially after the dismissal of Akid where they never let their guard down."
"We can certainly see a lot of potential from this team, but the main weakness is our front line and despite some nice work, our final third is still the issue I have to sort out"
"The only noticeable difference between the two teams was the ability of the Bruneian players to grab their chances while we can't as we do not have a target man and hopefully I can find one during the Datuk Seri Musa Haji Aman Cup Inter-District Football Tournament to be held here starting on Monday," he added.