Bagan, who wore the crown in the 2014-15 season under coach Sanjoy Sen, are top of the table with 33 points from 16 matches. Aizawl have the same number of points as Mohun Bagan but are second owing to an inferior head-to-head record.
A victory for Mohun Bagan against Aizawl, whom they beat 3-2 in their first meeting, would win them the league.
If Aizawl are to cap their fairytale run and clinch an improbable title, the Khalid Jamil-coached side will have to win by a two-goal margin to seal the deal against Mohun Bagan.
A draw would see both teams' fate being decided in the last round of matches where Mohun Bagan host Chennai City FC and Aizawl take on Shillong Lajong in an away clash.
"It would be a very difficult job for us. They have got players like Jeje, Duffy, Sony, Anas and the goalkeeper is also doing so well," Aizawl coach Jamil said on the eve of the match.
"Mizoram players are very hardworking. They give 100 percent all the time, whether it's in practice or match," Jamil added when asked what made the difference this time for him and his unheralded wards.
The Mohun Bagan camp meanwhile are approaching the match with caution.
"We will give our best. It will be a difficult match for us," Bagan coach Sen said.
Mohun Bagan lost their last outing, a Group E AFC Cup game against Maldives' side Maziya Sports & Recreation Club by a solitary goal at home on Wednesday.
But coach Sen had fielded a second string team with only Jeje Lalpekhlua retained from their previous I-League engagement against Minerva Punjab FC.
Aizawl, on their part, will come into the game brimming with confidence having beaten Churchill Brothers 3-1 in the latter's own backyard.
Mohun Bagan's Scottish striker Darryl Duffy had scored a brace the last time the two sides met with Jeje netting the other goal. Mumbai FC recruits Jayesh Rane and Asutosh Mehta hit the back of the net for Aizawl.
Aizawl have lost just thrice this season winning 10 games and have stunned one and all by punching way above their weight.
Their foreign recruits Kamo Bayi, Alfred Jaryan and Mahmoud Amnah have played exceptionally well helped by strong local talent.
Mohun Bagan will depend heavily on Haitian star Sony Norde who has been in good form recently, scoring the late winner against Minerva.
Besides Norde, Duffy has also scored a bucketful of goals this season and at important junctures. Balwant Singh has also had a good run along with Japanese playmaker Yusa Katsumi.
It is expected to be the highest attended football match ever in Mizoram. Regulars at the ground expect around 12,000 people to attend -- a figure which will easily surpass that of the recent home match against Bengaluru FC, where Aizawl's crowd support was instrumental in holding the defending champions 1-1.
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