A horrendous performance by Mohun Bagan goalkeeper Shilton Paul enabled Mumbai FC beat last year's runners-up 2-1 and register their first I-League victory in a sixth round floodlit match at Vidyasagar Krirangan in Kolkata on Monday.
Mumbai FC scored in the first minute through Abhishek Yadav, and then found the net in the 41st minute through Bashiree Mohammed Abbas.
Bagan reduced the margin in the 60th minute through Snehashish Chakraborty.
The day started on a sad note for Bagan, as their main custodian, Sangram Mukherjee, was ruled out of the match after meeting with an unfortunate accident in the morning.
Sangram slipped in the bathroom and fractured his right foot, forcing coach Karim Bencherifa to field Shilton.
On a day when Shilton blundered, the Mumbai side's goalkeeper A C Nithinalal came up with good saves, helping the visitors collect three points.
Nithinlal was later adjudged man-of-the-match.
A sloppy display by Shilton saw the Mumbai outfit take an easy 1-0 lead just after the kick-off. A cross from the right was easily capitalised upon by Yadav, who headed the ball home.
In contrast, Mumbai FC custodian Nithinlal sparkled, denying every effort from Mohun Bagan strikers Edeh Chidi and Ishfaq Ahmed with good saves.
In the 15th minute, Chidi looked good for his sixth I-League goal this season but the Nigerian's attempt was thwarted by Nithinlal.
In the 34th minute, Manish Maithani fired in a long shot but Nithinlal once again stood tall.
Bagan got their best chance in the 39th minute when James Singh set it up for Ishfaq, who missed a sitter with an off-target header. It was more misery in store for the home outfit when Mumbai FC capitalised on another Shilton mistake to make it 2-0 in the 41st minute.
Shilton and rookie defender Sangram Mandi were engaged in a misunderstanding as the Bagan custodian advanced to grab the ball but failed to hold on to it. The free ball was brilliantly utilised by Abbas, who scored without any problem.
Down 0-2, Bagan substituted Ishfaq up front with Branco Cardozo and the change yielded results as the youngster helped his team reduce the margin.
Bagan pulled one back in the 60th minute when Branco's effort was stopped by Nithinlal, but Snehashish, who was lurking from behind, latched on to the loose ball and guided it home to make it 2-1.
Four minutes later, Chidi almost made it 2-2 but luck did not favour the Nigerian, whose right-footer hit the bar.
In another attack, Bagan had a fine shot at the goal in the 74th minute through a Marcos Pereira corner but again Nithinalal came to Mumbai FC's rescue.
Bagan tried their best to get in an equaliser but just could not beat Nithinlal.
Bagan have nine points from six matches, while Mumbai FC have six from as many outings.
