By Gabriel TanFollow @@gabetan13
Entering the game at the Majlis Perbandaran Selayang Stadium with just one point from their opening two games, the Red Giants were desperately seeking a win to kick-start their campaign.
But they fell behind in the 22nd minute when Karlo Primorac opened the scoring, before the Croatian striker made it 2-0 just seven minutes later.
And in the 72nd minute, Fazrul Hadi Kadri added a third for the hosts to wrap up the win and leave Selangor facing the embarassing prospect of a group stage exit.
The result also sent Sime Darby top of the group and a point ahead of Johor, who played out a thrilling 3-3 draw at home to ATM.
Having taken a 43rd-minute lead through Ezairady Khadar's opener, the hosts appeared to be cruising after Farid Ideris doubled their advantage three minutes after the break.
However, Shukor Adan pulled one back for the Armed Forces five minutes later and after Marlon Alex James grabbed the equaliser in the 73rd minute, he netted his second of the evening six minutes later to put his side ahead.
But Johor refused to give in and nine minutes from time, Hairul Nizam Hanif struck to earn his side a deserving share of the spoils.
Reigning Malaysia Super League champions LIONSXII are also staring at an early exit after a 1-0 defeat at Perak left them bottom of Group D with just a solitary point to their name.
In a keenly-contested encounter at the Perak Stadium, Azlan Ismail netted after a neat flick-on by Paulo Rangel in the tenth minute to hand Seladang all three points and keep them top of the group.
Sarawak remain second ahead of Kedah after both sides played out a 0-0 draw at the Darul Aman Stadium.
Over in Group B, PKNS FC are almost through to the quarter-finals after claiming a 2-0 victory over FELDA United at the Shah Alam Stadium.
Liberia international Patrick Ronaldinho Wleh continued his recent rich vein of form when he broke the deadlock five minutes after the half-hour mark, before adding a second in the 51st minute to seal the win for his side.
Over at the Sultan Ismail Nasiruddin Shah Stadium, Darul Takzim made it two wins in a row as they saw off T-Team's plucky challenge to record a 3-2 triumph.
After Hadin Azman had put the visitors ahead in the 23rd minute, Safee Sali struck five minutes later to give them a commanding lead.
But three minutes into the second half, Syamim Yahaya pulled one back for the T-Team, only for Harimau Selatan to reclaim their two-goal advantage right on the hour mark when Norshahrul Idlan Talaha found the back of the net.
Yet, the Titans refused to give in and hit back again in the 77th minue through a strike from Fazuan Abdullah, although they were just unable to find an equaliser as their opponents held on to the win.
Finally in Group C, Pahang remain top of the pile after overcoming an early setback to force a 1-1 draw at home to Terengganu.
Although they have been struggling for form in recent times, it was the visitors who took the lead when Ashaari Shamsuddin netted in the eighth minute.
But six minutes later, Matias Conti grabbed his second goal of the campaign to earn a point for Tok Gajah.
Defending champions Kelantan are level on points with Pahang but remain second on goal difference after a 1-1 draw at Negeri Sembilan.
The Red Warriors took the lead five minutes before halftime when Dickson Nwakaeme found the back of the net, but a minute before the hour mark, Fabio Leandro Barbosa scored to force the draw for the hosts.
Tuesday's Malaysia Cup Results
Sime Darby 3-0 Selangor
Johor 3-3 ATM
T-Team 2-3 Darul Takzim
PKNS FC 2-0 FELDA United
Negeri Sembilan 1-1 Kelantan
Pahang 1-1 Terengganu
Kedah 0-0 Sarawak
Perak 1-0 LIONSXII
Image courtesy of Md Azreen (Corner Flag)