Sueoka, who replaced Reisangmei Vashum in the 55th minute, brought the 40,000-odd crowd on their feet, scoring in 71st minute. His curling shot from the edge of the box found the Semen Padang net.
East Bengal, who are eyeing their maiden semi-final berth in the tournament, face the Indonesian outfit in the return quarter-final leg at the Agus Salim Stadium, in Padang, on September 24.
Goan heavyweight Dempo FC is the only Indian side to have made the AFC Cup semi-finals, in the 2004-05 season.
The win must have brought relief to East Bengal’s newly-appointed Brazilian coach Marcos Falopa, who was under pressure after taking over the reins from the hugely successful Trevor James Morgan.
The red-and-gold brigade had an unconvincing start as they relied on long balls. To make matters worse, Sudanese recruit James Moga did not look fully fit.
The visitors dominated the first half, which failed to yield any goal. In fact, things could have been different had Padang not missed two easy sitters early into the match.
East Bengal survived an early scare, but full credit should be given to goalkeeper Gurpreet Singh, who stood tall under the bar, thwarting two back-to-back attempts from the Indonesian outfit.
Gurpreet first denied Wilson, who made a fine run from the left flank, and Muhammad Nur Iskandar took a powerful shot from the melee, but the lanky goalkeeper again made a brilliant save in the seventh minute.
Minutes later, the East Bengal camp again panicked but the Padang outfit wasted a sitter. Yu Hyunkoo tested Gurpreet with a shot that dipped a lot and the rebound fell in front of Ronaldo Moro, whose angled header in front of the goal was wayward.
Having escaped the initial Padang onslaught, East Bengal had their first chance in the 22nd minute when Chidi Edeh set up Vashum, who had the full view of the net, but, to the horror of the home side fans, the latter failed to get hold of the ball.
In the dying minutes of the first-half, East Bengal had an outside chance with the Padang goalkeeper Jandia Eka Putra fumbling but the defence cleared the ball before an off-colour Moga could take the possession.
Moga was equally lacklustre in the second half. The former Pune FC forward wasted an opportunity in the 56th minute.
But the all-important move came in the 55th minute when Sueoka replaced Vashum and the spectators cheered loudly anticipating a positive vibe.
The Japanese did not disappoint as his powerful curling shot was enough to give East Bengal three points and hope for making it to the last four.
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