The match originally scheduled to hold on Wednesday, but was shifted after the new COVID-19 constraints did not allow Celtic to travel to Nigeria.
The DStv Premiership outfit entered the second leg trailing the Nigeria Professional Football League outfit by two goals, but they once again made wholesale changes for the encounter, as they did in the previous round.
However, River United signalled their intent early on when Godwin Aguda opened the scoring in the first half, making it 3-0 on aggregate for the hosts.
Celtic’s fate was virtually sealed just before the halftime break when Aguda bagged his second goal of the game to hand the Nigerian outfit a comfortable lead.
The Port Harcourt based team sealed the victory and a spot in the next round thanks to Fortune Omoniwari’s strike five minutes after the halftime break.
Rivers will now lock horns with fellow Nigerian Premier League outfit, Enyimba in the next round of the competition.