Mohammedan Sporting Club Limited, on the other hand, crashed out of the tournament despite winning the first game of the day against Afghanistan outfit Shaheen Asmayee FC. The Black and Whites beat Shaheen FC 2-1 in their last Group B encounter.
Following the end of the group stage, Chittagong Abahani finished their Group B campaign at the top of the points table with five points from three matches, winning one and drawing two.
Manang Marshyangdi and Mohammedan have the same number of points but head-to-head record put the former ahead of the latter.
The port city outfit will face South Korean club Pocheon Citizen FC in the second semi-final at the same venue this Monday while Manang take on Group A winner TC Sports Club of Maldives in the other last four battle on Sunday.
It was not the best of the starts for the home side as they conceded an early goal with only three minutes into the clock. Manang's last-match hero Afeez Olawale Oladipo put his side ahead heading home a headed pass from Anil Gurung.
Afeez, the Zambian striker, stunned the home side once again by doubling the lead in the 22nd minute, placing the ball into the far post after collecting a long ball from the centre of the pitch.
Veteran defender Nasir Uddin Chowdhury pulled one back for Chittagong Abahani 10 minutes later, heading home a cross from midfielder Jamal Bhuiyan.
The host kept on piling pressure for the equaliser after resumption and levelled the margin in the 63rd minute. Augustin Walson converted a penalty after Adama Sissoko was penalised for handball.
In the day's second game, it was a contrasting display by Mohammedan, who have been struggling for quite a while now. They won 2-1 thanks to Gambian forward Dawda Ceesay, who netted a superb brace.
Ceesay gave the Black and Whites the breakthrough in the 32nd minute with a lovely finish before doubling the lead in the 69th minute with another spectacular strike. The Gambian slid past his marker before unleashing a curved left-footed strike from 25 yards that sneaked into the top right corner.
Amiruddin Sharifi, who netted a hattrick against Manang in the last match, scored the consolation for the visiting side three minutes before the end of stipulated time from the penalty spot.
Ctg Abahani 2
(Nasir 32, Walson 63 - P) 2 Manang
(Afeez 3, 22)
(Dawda 32, 69) 1 Shaheen
(Sharifi 87 - P)
SEMI-FINAL LINE UP
TC Sports Club v Manang Marshyangdi, Sunday
Chittagong Abahani v Pocheon Citizen, Monday