The Indian side take a 1-0 aggregate lead into the clash at the Agus Salim Stadium in Padang thanks to Ryuji Sueoka's goal off the bench in the first leg.
Sueoka had only been on the pitch for 15 minutes when he broke the deadlock to give Bengal the win, while Padang were also kept from scoring an all-important away goal.
Marcos Falopa was pleased with his side's home win on Tuesday and, desite their domestic season not having started as yet, he feels his squad are becoming fitter all the time.
On the tie, Falopa told the AFC website: "Our aim was to win the home game and approach the away fixture in the right frame of mind.
"Even though we haven’t played many matches, the players are quickly becoming match fit."
Bengal are unbeaten in the competition this season, and have also won once and drawn twice on the road on their way to the last eight.
For Padang, the defeat to Bengal was their first of the season in the competition, having qualified top of Group E with an unbeaten record before overcoming Vietnamese side Shb Da Nang at the last-16 stage.
And Padang manager Jafri Sastrak believes his side need more luck in the second leg if they are to turn the tie around.
Speaking about the first leg, he said: "In this end to end fight, we also had our chances but luck deserted us and favoured our opponents."
Sastrak will have decisions to make on his squad, with the Indonesian Premier League leaders facing a domestic clash on Monday against fifth-place Persiba Bantul.
The winners of the AFC Cup tie will meet either Kuwait SC or New Radiant in the semi-final, with the former leading 7-2 against the side from the Maldives after the first leg.
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