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Spurs have not won any silverware since they lifted the League Cup in 2008 and Mourinho, who has won the competition four times, said he was looking to set the record straight and end the club's trophy drought.
"I think it's my biggest game since coming to Spurs. In the perspective of the club chasing silverware for many years, I would say so," Mourinho said.
"For me every competition is important... That's my way of looking at things and especially in a club without silverware in, I think, more than one decade. Every competition becomes even more important.
"If we win two matches we win a trophy - two difficult matches of course - which I think would be a very good thing for the club and the players."
The Portuguese boss also said he was waiting to know the revised date for the Premier League fixture at home to Fulham after the New Year's Day London derby was called off due to a COVID-19 outbreak in the visitors' camp.
"I'm not happy with the fixtures since day one and in day one I was far from imagining that I would have a game postponed," he said.
"To speak about the Carabao [League] Cup final, I refuse to do it, because maybe Brentford plays the final and not us.
"But I would like to know when I play against Fulham, refusing totally to be punished by a congestion of crazy fixtures like we were in the beginning of the season."