Strikes from Shaiful Esah and Madhu Mohana, as well as an own-goal from UiTM captain Ahmad Shahir, secured a win for the Singapore outfit against the team from Malaysia's third tier.
Despite many observers claiming that the result was the very least LIONSXII should have achieved, Hariss was delighted with how his team performed during the potentially tricky tie.
"The game was not easy, and UiTm gave us a run for our money, especially in the second half. However, we stuck to our task and I think we did a very professional job," the talented 21-year-old told ESPNSTAR.com.
"At no point in time did we look down on them or think that it was going to be an easy game. So I think it is credit to us that we got the result we did.
"A clean sheet always gives more confidence to the goalkeeper and defenders, as well as to the team as a whole. It was also good to get some goals, we could have got more, but I think three was decent. We are now looking forward to the next round," he added.
LIONSXII have enjoyed a stellar start to their debut Malaysia Super League campaign, a run of results that already includes notable wins over top guns Terengganu and Negri Sembilan en route to the fourth place they currently occupy.
With a place in the second round of the FA Cup secured, Hariss is delighted that LIONSXII are performing well on two fronts. Nevertheless, the amiable midfielder has urged his side to carry on the momentum when they reconvene after Singapore's World Cup qualifier against Iraq on February 29.
"It is important to keep our current momentum going after the international break," Hariss declared.
"We still have a long league season ahead of us, and we also have the next round of the FA Cup and the Malaysia Cup still to come. But of course, it is exciting to be involved on several fronts."
LIONSXII's next league game is against Felda United at Singapore's Jalan Besar Stadium on March 6, while they entertain Premier League team NS Betaria in a second round FA Cup clash at the same venue four days later.