A 1-0 defeat to champions Albirex Niigata (S) at Jalan Besar Stadium on Thursday night meant Home United finished bottom of Group A and were unable to progress into the last four of the 2017 Singapore League Cup.
Tsubasa Sano's second-half goal extended the Protectors' winless run to four games in all competitions. It's a worrying sign ahead of the two-legged AFC Cup ASEAN Zonal final against Philippines side Ceres-Negros early next month.
Croatian hot shot Stipe Plazibat also failed to score for the first time in a domestic game this season.
Having to play without the suspended duo of Afiq Yunos and Khairul Nizam, the Protectors struggled to impose themselves in the game, and could have gone a couple of goals down in the first half.
Ryota Nakai's close-range shot on eight minutes was kept out by Hassan Sunny at his near post before Kento Nagasaki's 27th-minute free kick hit the upright.
Sano and Shoichiro Sakamoto also headed wide as the first half somehow ended goalless.
However, the White Swans would break the deadlock eight minutes after the restart. Top scorer Sano fired into the top corner after Koki Sato's pass was dummied into his path by Nakai.
Home coach Aidil Sharin reacted by introducing Faris Ramli to replace Iqram Rifqi on the hour mark. But the Singapore winger found the going tough against a stubborn Albirex defence led by Yasutaka Yanagi.
Izzdin Shafiq did have an ambitious attempt from range on 62 minutes which sailed just over Yosuke Nozawa's bar.
They did create an excellent opportunity 10 minutes before the end. However, Croatian forward Marijan Suto contrived to head over Sirina Camara's left-wing cross from close range.
The result meant that Albirex finished top of Group A with seven points to progress into the semifinals.
The White Swans were joined by Warriors FC in the last four. The uniformed outfit edged Hougang United out for the runners up spot in Group A after the two sides played out a 2-2 draw at Hougang Stadium.
The League Cup semifinals will be held next Tuesday after the concluding Group B matches on Friday night.
Home United: Hassan Sunny (GK, C), Shamil Sharif, Abdil Qaiyyim, Hariss Harun, Luqman Ismail (Sirina Camara 55'), Haziq Azman (Aqhari Abdullah 75'), Izzdin Shafiq, Iqram Rifqi (Faris Ramli 62'), Sufianto Salleh, Marijan Suto, Stipe Plazibat
Albirex Niigata (S): Yosuke Nozawa (GK), Hiroyoshi Kamata (Rui Kumada 37'), Yasutaka Yanagi, Takuya Akiyama, Naofumi Tanaka, Shoichiro Sakamoto, Shuto Inaba (C), Kento Nagasaki, Koki Sato (Ryuya Motoda 73'), Ryota Nakai (Kenya Kodama 90'), Tsubasa Sano