Despite a barren first half, goals from Osas Okoro and Peter Eneji in the second ensured Salisu Yusuf's men subdue the Leone Stars at the Cape Coast Stadium and advance to the group stage.
And the Akwa United man, who blamed fatigue for their first half poor display, admitted Abubakar Karama's men were tough to beat.
"We are happy getting a victory in the end. It was very tough beating Sierra Leone," Aremu told Goal.
"We arrived on Sunday night and everyone knows we played our last league game on Saturday before coming to Ghana. We couldn't even have a proper training.
"I must give kudos to my team mates. We fought hard as a team even with the tiredness of arriving Ghana late and still won the match. Our experience and composure really helped us and gave us the victory.
"Sierra Leone really gave us a difficult game, even though they had no star within them, we knew they will be tough because they have been training together for days."
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