By Gabriel Tan
The Young Tigers are currently ahead of fourth-placed Albirex Niigata only on goal difference and head into their final game of the campaign looking to sew up third spot.
However, with the Stags also needing a victory to wrap up the title, both sides will have plenty to play for at the Jalan Besar Stadium.
But despite the high-profile nature of the clash, Ong believes it is imperative his young charges rise to the occasion as that is something most of them will be facing when they represent the Malaysia Under-23 side at next year's Southeast Asian (SEA) Games.
"The boys know what we have to do if we want to finish in third place," he told ESPNSTAR.com exclusively.
"They will be up to the task and they know they have to take on the challenge of such a big game.
"It might be the same scenario in the future when they play in international tournaments and this will help prepare them mentally for the pressure of such games."
Ong, who is on very good terms with Tampines coach Tay Peng Kee, insists he will not be doing his old friend any favours on Friday and is expecting an open, entertaining encounter.
"Both sides need to win," the ex-Malaysia international added. "And we always go out to play attacking football.
"That is our style and it will be a matter of reacting to the situation in the match itself."
Regardless of whether or not they pip Albirex to third place, Harimau have already met their pre-season target of finishing in the top five in their first season of playing in Singapore football's top flight, something Ong believes they can be proud of.
"If you look at the whole season, I've played a team with an average age that's under 21 years old," he stressed.
"We also don't have any foreigners in our side and many times this year, we've had to do without our national team players whenever they're called up for international duty.
"We've also had a hectic schedule playing in various tournaments and with that in mind, finishing in the top five is a tremendous result. Realistically speaking, it's a very good achievement."
Ong has also confirmed Friday's game will be the last time vice-captain Affize Faisal and midfielder V. Kavichelvan will be pulling on the Harimau Muda jersey, as they will no longer be eligible to play for the U-23 side in 2013.