By Gabriel Tan at the Yishun Stadium
The visitors took the lead five minutes before the break when Qiu Li went on a dazzling run through the DPMM defence before laying the ball off for John Wilkinson to fire home.
However, their hopes of victory were dealt a severe blow in the 55th minute when Masrezwan Masturi received his marching orders.
Buoyed by their numerical advantage, the hosts, who are currently top of the Great Eastern-YEO's S.League, pushed forward and carved open the Home backline on several occasions but were ultimately kept at bay by a stunning performance from Lionel Lewis in goal.
And while he admitted his goalkeeper had played well, Protectors coach Lee Lim-saeng insists the victory was only possible through a well-rounded team effort.
"He [Lewis] made good saves quite a number of times but we also created many chances," the former Korea Republic international said after the game.
"Of course I'm very happy with the performance and I'm grateful for what they gave on the pitch. They did their best to help their team-mates; I want to give them credit for that.
"It was a very tough game for us tonight [Thursday], so you could say it was one of the best performances this season in terms of the character shown by the players."
The Protectors entered Thursday's game missing four key players through suspension, including captain Shi Jiayi and top scorer Frederic Mendy, and it certainly showed early on as DPMM twice came close to scoring in the opening half-hour.
First, Adi Said left fly with a 25-yard effort that forced Lewis into a fantastic diving save, before his brother Shahrazen fired too close to the Home custodian after being picked out by a pinpoint cross from Basiru Osman.
However, it was the Protectors who went ahead in the 40th minute thanks to a moment of brilliance by Qiu, who picked up the ball from a long throw by Lewis and went on a terrific run through the middle, leaving two defenders in his wake, before squaring the ball to Wilkinson. With only Wardun Yussof to beat, the ex-Singapore international made no mistake in sliding his shot into the bottom corner to give his side the lead.
However, Home's joy soon turned to anger ten minutes into the second half when Shahrazen collapsed in a heap after getting into a tussle with Masrezwan. After pondering his decision for a few moments, referee Sukhbir Singh handed the Protectors winger a straight red, adjudging that he had lashed out at his opponent with an elbow.
With a man advantage, DPMM began to dominate proceedings and came close to equalising in the 76th minute when Shahrazen found space in the box and nodded just wide, before Ivan Jerkovic looked odds-on to score after the ball fell into his path 15 yards out, only for Kenji Arai to block it with a brave stooping header.
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With DPMM coach Vjeran Simunic furiously urging his team on by the touchline, the hosts summoned one final push in the dying minutes but just could not find a way past an inspired Lewis, who was standing in for Shi as captain for the night.
First, he did well to hold on to a fierce shot by Abu Bakar Mahari two minutes from the end, before coming up with the save of the game in injury-time when he produced a brilliant reflex stop to claw away Jerkovic's bicycle-kick from point-blank range, after Tales Dos Santos had nodded the ball into the Croat's path.
Speaking after the game, Simunic was unwilling to openly criticise Singh's performance after his side were denied a penalty appeal for handball towards the end, and suggested that Home had won on the night thanks to a combination of excellent goalkeeping and good fortune.
"I said before the game that Lewis is the best keeper in the S.League," the Croatian tactician said. "And I think today [Thursday], God and Lewis saved Home United.
"And somebody else. I cannot say who - make a guess.
"Everyone said it [the shout for handball] was a clear penalty but I can't give my views because I'm the coach."
While DPMM's hopes of Singapore Cup glory have now been ended, they are still five points clear of Home at the top of league table.
DPMM FC: Wardun Yussof, Helmi Zambin, Subhi Abdilah, Tales Dos Santos, Sairol Sahari (Abu Bakar Mahari 78'), Rosmin Kamis, Ivan Jerkovic, Azwan Saleh (Awangku Fakharazzi 70'), Adi Said (Najib Tarif 46'), Basiru Osman, Shahrazen Said.
Home United: Lionel Lewis, Sofiyan Abdul Hamid, Nor Azli Yusoff, Kenji Arai, Rosman Sulaiman (Indra Sahdan Daud 87'), Rhysh Roshan Rai, John Wilkinson, Jeremy Chiang, Firdaus Idros, Masrezwan Masturi, Qiu Li.