Ricki Herbert's United side made a winning start to the inaugural season of the new competition by overcoming Kerala Blasters 1-0 on Monday, but are likely to face a stern test against an Atletico team that cruised to a 3-0 victory over Mumbai City.
But United co-owner Abraham is adamant his players have the fighting spirit necessary to claim all three points from the encounter in Guwahati on Thursday.
"Kolkata is a tough side but we are a young team, we will give our heart. We'll put up a fight like no one has ever seen," Abraham said.
"They are a bunch of warriors out there."
With both United and Atletico in action on Sunday, squad depth could play a crucial role as the two teams look to avoid early fatigue and maintain their strong starts, although they will each be coming up against sides that produced disappointing performances in their respective opening encounters.
United take on a Goa side beaten 2-1 at home by Chennaiyin on Wednesday, while Kolkata host a Delhi Dynamos outfit that was held to a goalless draw by Pune City a day earlier.
Pune visit Mumbai in their next encounter with their hopes of victory boosted by the news that the hosts' captain Syed Rahim Nabi will be out for up to three weeks due to an ankle injury suffered in the defeat to Kolkata.
A post on Mumbai's Facebook page read: "Syed Nabi will be out for up to three weeks. After an MRI, the medical team has verified that there is no fracture or a ligament tear. He has suffered a partial sprain in his ankle ligament and is undergoing rehabilitation."
Elsewhere, Chennaiyin will look to build on their opening success next Tuesday when they welcome Kerala to the Jawaharlal Nehru Stadium.
