By Gabriel Tan at the Bishan Stadium
SAFFC went ahead in the 38th minute when Japanese winger Tatsuro Inui curled home a terrific freekick, although Protectors captain Shi Jiayi equalised in first-half stoppage time when he found the back of the net with a diving header from a Qiu Li corner.
However, a shocking own-goal by Rosman Sulaiman five minutes after the break handed the advantage back to the Warriors, before some excellent defensive work in the closing stages ensured the visitors had a one-goal lead to take back to the Choa Chu Kang Stadium for Monday's return leg.
With SAFFC coach Richard Bok absent, the reins were handed to his assistant V. Selvaraj, who didn't see any reason to meddle much with a winning formula, making just one change to the side that inflicted a first home defeat of the season on Great Eastern-YEO's S.League leaders DPMM FC ten days ago by bringing in veteran Noh Rahman for Razaleigh Khalik.
Seven minutes in, the Warriors carved out their first chance when Inui threaded a neat ball through to Shimpei Sakurada, who failed to connect cleanly with his strike and scuffed a shot narrowly wide.
Six minutes later, it was Inui's turn to be presented with a shooting opportunity when Zufadli Zainal Abidin went on a bursting run down the left and whipped in a cross that eventually made its way to his Japanese team-mate. However, with plenty of time and space, the skilful winger could only manage to screw an effort off target.
In a keenly-contested opening half-hour which failed to produce many clear-cut chances, both sides were largely restricted to shots from distance, with Warriors marksman Mislav Karoglan looking particularly frustrated in his new withdrawn role behind striker partner Fazrul Nawaz.
Instead, it looked like it would take a moment of magic to break the deadlock, which duly arrived seven minutes before the break when the visitors were awarded a freekick on the edge of the area, presenting Inui with the opportunity to fire home a sublime effort that arrowed into the far corner.
Stunned into action at going behind, Home then started to pile the pressure on their opponents in a frenetic close to the opening period, but both Franklin Anzite and Frederic Mendy failed to convert good openings, with the latter forcing Shahril Jantan into a fine save after meeting a cross from Shi with a firm header.
Nonetheless, from the resultant corner, SAFFC inexplicably failed to pick up the Protectors skipper, allowing him all the time and space he needed to stoop low and glance his header into the back of the net.
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Yet, the hosts found themselves behind again just five minutes after the restart in quite bizarre circumstances, when Rosman looked poised to deal with a low cross from Karoglan but instead sliced his clearance over a hapless Nazri Sabri.
It was an awful moment for Rosman, who was immediately replaced by Jeremy Chiang, as well as Nazri, who was deputising for the injured Lionel Lewis, but the goalkeeper did well on the hour mark to keep out a rasping drive by Karoglan, after the striker cleverly created space for himself on the edge of the area.
Two minutes later, Home had a good chance to equalise when Qiu picked up possession on the left side of the box and whipped in a low ball that was just out of the reach Mendy, who had been waiting unmarked six yards out.
Despite having a lead to hold on to, the Warriors remained the more adventurous of the two teams and should have been awarded a penalty in the 74th minute when Sakurada jinked his way past two men and was scythed down in the box, only for referee Mohd Yazeen Buhari to wave play on.
Eight minutes from time, Nazri came to his side's rescue again when he did well to block Ruzaini Zainal from point-blank range after spilling a shot from Shukor Zailan, before thwarting the SAFFC substitute once more a couple of minutes later, after he had raced through down the left following an untimely slip from Nor Azli Yusoff.
And with time fast running out, the Protectors mustered one final push to grab an equaliser and nearly did so in the 86th minute when Anzite wasted a glorious opportunity after failing to keep a close-range header down.
A minute later, a low ball by Firdaus Idros caused pandemonium inside the SAFFC box before falling to Mendy, who looked odds-on to score from six yards out. However, the Frenchman could only watch in vain as his effort cannoned away to safety off a fantastic last-ditch block by Marin Vidosevic, as the Warriors held on for a vital triumph.
Home United: Nazri Sabri, Nor Azli Yusoff, Sofiyan Abdul Hamid, Kenji Arai, Rosman Sulaiman (Jeremy Chiang 52'), Franklin Anzite, Shi Jiayi, John Wilkinson (Shotaro Ihata 55'), Indra Sahdan Daud (Firdaus Idros 46'), Qiu Li, Frederic Mendy.
SAFFC: Shahril Jantan, Noh Rahman, Daniel Bennett, Marin Vidosevic, Zulfadli Zainal Abidin, Tatsuro Inui, Shukor Zailan, Shimpei Sakurada, Aliff Shafaein (Ruzaini Zainal 71'), Mislav Karoglan, Fazrul Nawaz.