The Eagles surrendered a four-goal lead to be held to a dramatic 4-4 draw by the Leone Stars in Benin City last week and will now need to win in Freetown today to secure qualification to the AFCON in Cameroon.
Nigeria still lead their qualifying group with seven points from three matches.
Rohr has backed his team to win the three points at stake in Freetown despite the tough conditions in Sierra Leone.
“The objective is to win the game,” he said.
“We wanted at least four points from the two matches (vs Sierra Leone) to qualify for AFCON, and that’s still possible.
“We will play our game, playing forward, scoring goals, but we have to defend better than we did in Benin.”
He added: “It will be difficult against a good team, but believe in my team.
“The players will fight till the end of the match, give their best.”
However, Rohr admitted the team will miss Napoli striker Osimhen, who injured his shoulder in the first match in Benin.
“We will Osimhen miss him for a long time, but other players are here to come in,” he said.”
One of the Eagles goal scorers in Nigeria Samuel Chukwueze, defender Leon Balogun and forward Emmanuel Dennis all trained fully Monday at the Siaka Stevens Stadium in Freetown to clear injury fears in the squad.
Today’s match will kick off at 4pm local time, which is 5pm in Nigeria.