The new season of Federation Cup kicked off with contrasting fortunes for title contenders Mohammedan Sporting Club and Abahani, as the two heavyweights featured in Group B matches at different venues on Tuesday.

Last season's runners-up Mohammedan suffered a shock 1-0 defeat to Rahmatganj MFS in Dhaka, while 12-time champions Abahani cruised to a commanding 3-0 victory over Chittagong Abahani in Cumilla.

Mohammedan, who hold 11 Federation Cup titles, came into their opener riding high on confidence after defeating Bashundhara Kings 1-0 in a Bangladesh Premier League encounter just days ago. However, they were undone by Rahmatganj, a minnow possessing the giant-killers tag.

The result could be considered an upset for Mohammedan, even though they had suffered two defeats and one draw against Rahmatganj in their last five Federation Cup meetings between 2015 and 2023.

The match, held at Bashundhara Kings Arena, saw Rahmatganj goalkeeper Mamun Alif in inspired form, thwarting several attempts by Mohammedan forwards, including Ghanaian Boateng Ernest and Nigerian Emmanuel Sunday.

The decisive moment came in the 82nd minute when Rahmatganj's Rajon Howlader found the net with a well-taken near-post drive. Mohammedan's frustrations boiled over in the 85th minute when Jahid Hasan Shanto received a red card for striking Egyptian forward Mostafa Hammad, leaving the Black and Whites unable to mount a late comeback.

Coach Alfaz Ahmed's decision to rest six players, including key forward Souleymane Diabate -- ahead of Saturday's league clash against arch-rivals Abahani -- appeared to backfire as his side failed to find cohesion or sharpness in the attack.

Meanwhile, at Shaheed Dhirendranath Datta Stadium, Abahani executed a clinical performance against Chittagong Abahani. Forward Suman Reza gave the Sky Blues an early lead in the 17th minute with a header that narrowly crossed the line after hitting the far post, sparking a near seven-minute halt in play as the port city side contested the decision.

After the interval, Mohammad Ibrahim doubled the lead in the 76th minute, capitalising on a long ball before making a darting run, slotting home with a powerful strike. Defender Yeasin Khan added the finishing touch in the 86th minute, tapping in a low cross from Enamul Islam Gazi to seal the victory.

While Abahani's form suggests they are early favourites for the title, the defeat adds early pressure on Mohammedan, who now face an uphill battle in the five-team group stage.