Leonce Dodoz' first-half strike was cancelled out by Enrique Esqueda after the break as the Kolkata giant dropped crucial points in the race for the title.
Johnny Acosta's suspension meant Salam Ranjan Singh got to play football for the first time since India's defeat to Bahrain in the Asian Cup on 14 January. Toni Dovale featured in a straight swap as young Jaime Santos was preferred on the left wing.
Stanley Rozario made one enforced change and two other alterations from their home defeat to Mohun Bagan. Kareem Omolaja came in for former India international Govin Singh who was suspended. Remsanga Fanai and Duatsanga also made their way into the Aizawl set up.
Salam's rustiness showed early on as he gave the ball away for the first real chance of the game. Alfred Jaryan released the ball for Ansumana Kromah who was closed down by Chullova, thereby preventing the Liberian from taking a proper shot on target in the ninth minute of the game.
Halfway through the first half, Aizawl got the deserved lead with Salam guilty yet again. The former Bengaluru FC defender played Dodoz onside from a Jaryan long ball. With East Bengal keeping a high line, the Ivorian had it easy as he had just the keeper to beat. Dagar came off his line and Dodoz chipped the ball in with panache to draw first blood.
East Bengal found it hard to break the Aizawl defence as the only threatening chance the hosts had was a shot from range by Danmawia which Lalawmpuia managed to tip over the bar.
Controversy ensued right on the stroke of half time when Rakshit Dagar had released the ball with his palms and Kromah intercepted it to slot the ball home but the goal was disallowed. Instead, referee Umesh Bora deemed it to be obstruction by the Aizawl striker and booked the striker.
Four minutes post the change of ends, Jobby Justin managed to graze the outer side-netting but the Red and Golds gained momentum after Menendez brought on Samad Ali Mallick and Toni Dovale.
Dovale held the ball up for an overlapping Samad who made a run on the right. The fullback's cross into the box was missed by an otherwise excellent Lalawmpuia. Esqueda jumped in from behind Kareem Omolaja and headed into an empty net.
Omolaja was dismissed five minutes after the equaliser for a moment of madness. He got his marching orders after showing dissent, following up for a rash challenge on Justin.
The hosts could not go ahead despite the numerical advantage on the field.