Moriri, who earned a recall for the trip to Sierra Leone, admitted the team will miss the talents of Schillo for the 2012 Africa Cup of Nations qualifier.
Pienaar walked away as man of the match in the national team's previous two fixtures against Ghana and Niger, but he's been ruled out of Sunday's match due to a groin injury.
Moriri said: "We cannot run away from the fact that Steven Pienaar is the most important member of this team and he played an important role in the previous games.
"We are going to miss him, but there is nothing we can do about it because it is an injury, but the guys who are around we have to soldier on and make him proud by winning the game."
Moriri further cautioned the team to use the chances they create. The Mamelodi Sundowns attacker was reflecting on Bafana's last visit to Freetown, where they lost 1-0 on 14 June 2008.
He said the trip was marred by the team's woeful finishing. "I can remember the game vividly. We created so many chances and missed all of them, now we have to make sure we convert the chances we create," added Moriri.
"If you want to be the best in Africa you have to play good away from home and we are all aware of that... the earlier we collect the points the better for us, because you never know what will happen especially when you are playing away from home.
"We have to be one step ahead. I think the fact that we are going there for the second time means we are better prepared because we know what it is all about playing there," he concluded.