The Liberian international struck in the second half to hand the hosts their first three points of the season
Both squads were playing their third game in seven days and it was clear to see they were fatigued.
Despite both teams fielding their lethal strikers upfront - Marlon Alex James and Arostegui for ATM and Karlo Primorac and Patrick Wleh for PKNS - the first half was goal-less and low on goalmouth action.
The pep talks by the coaches turned things around in the second half with both teams going all out and attacking moments after the game resumed.
James came close to opening the scoring but his first-time shot was saved by Remezey Che Ros. PKNS then hit the crossbar a few minutes later through Aminuddin Noor.
Wleh then got what turned out to be the winner when he received a fine through ball from Shahrul Azhar and tucked it into the goal past Adney Hussein in the 72nd minute.
Last year’s Goldeb Boot winner James could have scored an equaliser in stoppage time but his free-kick came off the woodwork.
This was PKNS’s first three points of the season after their defeat in the opening game against Terengganu, while ATM suffered their second defeat in a row after losing to Sime Darby in the FA Cup last Tuesday.