The deal stipulated that each FA will be represented by an under-23 team, but FAM gave leeway for Singapore's LionsXII to include players up to the age of 28, with the view that an under-23 team would be restricted by players in full-time National Service.
But only one day before Singapore's storied cross-Causeway rivalry is renewed, with the LionsXII hosting Selangor tonight in a highly-anticipated Malaysian Super League (MSL) clash at the Jalan Besar Stadium, FAM vice-president Hamidin Amin dropped a bombshell, revealing that the under-23 ruling could be re-introduced next season.
"If the LionsXII win the league, the Malaysia Cup and the FA Cup, we will have a problem. We all want a competitive league but we have to be fair to the Malaysian teams.
"So, if the LionsXII collect all three trophies we will have to go back to having an under-23 team," said Hamidin, who is in town as general secretary of Selangor.
There are 12 players in V Sundramoorthy's 29-man LionsXII squad who are above the age of 23, including skipper Shahril Ishak, Isa Halim, Baihakki Khaizan and Shahdan Sulaiman.
They have formed the backbone of the side that has risen to third in the 14-team MSL and qualified for the quarter-finals of the FA Cup.
"The media in Malaysia are already questioning me on why Harimau Muda, who are playing in the S-League, are participating with a full under-23 team but the LionsXII are allowed over-aged players.
"We will have a brainstorming session with Singapore officials and we will see after this season," said Hamidin.
Malaysia's Harimau Muda are currently unbeaten in the 13-team S-League and have yet to concede a goal. Their average age is below 21 years.
"You can want to win and develop players at the same time but you must sacrifice something," said Hamidin, who suggested allowing the LionsXII a bigger squad - between 35 and 40 players - as a possible solution if the under-23 ruling is eventually enforced.
Speaking to TODAY, LionsXII captain Shahril said: "It of course motivates us that it has crossed people's minds that we might be able to win all three trophies, but it's still early and we won't get carried away.
"Personally, I'm thankful the FAM have given us the opportunity to play in their league and hope that I do well enough this year and perhaps take my chances at Malaysian clubs after that."
LionsXII defensive midfielder Isa Halim, 25, warned of negative side effects that may arise from a possible change.
"If it does come about, it may backfire in the sense that Malaysian fans do want to see a strong Singapore side competing in the league," he said.
FAS president Zainudin Nordin declined to comment on the possibility of a change as he has not been officially told of any proposed revision of the age rule.
And Isa said: "What happens next season is secondary, what matters is this year, and if we can be treble champions, we will end things on a high and that would be great."