Benjamin Mora was left bemoaning a crucial penalty decision that went against Johor Darul Ta'zim (JDT), which would ultimately cost his side a place in the FA Cup semifinals.
In their quarterfinal, the reigning champions lost 4-3 on aggregate to Pahang, despite winning Sunday night's second leg 2-1 at Larkin Stadium.
Pahang will now go face Negeri Sembilan in the last four on April 29, while Kedah will host Terengganu in the other first leg tie on April 30.
JDT seemed in control at 2-0, thanks to early goals from Gonzalo Cabrera and Gabriel Guerra. But they were dealt a sucker punch when Mohamadou Sumareh struck three minutes from time to send the Cup holders crashing out.
The Gambian's goal proved too much for JDT, who came into the second leg trailing 3-1 from their trip to Kuantan on April 1.
Mora was livid that his team were denied what appeared to be a clear penalty early in the second half. Afif Amiruddin hacked down Guerra in the box, but the referee chose to let play continue.
"To me, it was a poor decision and it cost a game," lamented Mora via the Southern Tigers Facebook page.
"We started with two goals and were pushing for more, but when a clear penalty was not awarded to us, it disrupted and eventually cost us the game.
"I think the players gave 100 percent, but it's our fault because when we went for the away game we did not take full advantage of that."
Defeat not only ended JDT's interest in the competition, it also meant they have now missed out on two trophies after surrendering the Charity Shield to Kedah in January.
After a slow start to the season, the Southern Tigers are slowly beginning to find their form in the Malaysia Super League (MSL) and are on a five-game winning streak.
The victories have helped JDT take a three-point lead at the top of the MSL table.
Mora's men could potentially also miss out from the knockout stage of the continental AFC Cup, with only the group leaders guaranteed automatic passage from the group.
JDT are second behind Philippines Global FC with one game to go in Group F, but could advance as the best runners up.
The return leg of the FA Cup semifinals will, meanwhile, take place on May 13.