The Sea Robbers, who edged Polokwane City 1-0 in the Premiership on Wednesday, will host the Egyptians in their final Group A fixture at Orlando Stadium.
Pirates, on seven points, are three points behind Ahly; level with AC Leopards, and three points above bottom-placed Zamalek.
"This afternoon we get together again to plan for the match against Al Ahly," Lekgwathi said on his club's official website.
"One thing I am certain of is that although these guys have nothing to lose having already qualified for the next stage of the competition, they are a side that never compromises their integrity as one of the giants in the continent.
"So, to all fans going to the stadium, do not expect us to walk all over the Egyptians. They will come here to play football and try to win the match.
"We will take Thursday's session extremely seriously and will do our best to play our normal football and defeat them on Sunday.
"I therefore call on the nation, on behalf of Orlando Pirates Football Club, to rally behind the team on Sunday. We are in this as a nation and therefore every football lover will have to play a role on Sunday.
"We need a fully packed house. Please buy your tickets and make sure to bring your flag or vuvuzela to inspire us to victory. We beat Al Ahly in Egypt and I am sure we can do the same in Orlando."