Nicholson scored 29 points in Canada's 81-74 loss to the Dominican Republic on Saturday in the tournament's second round.
Only the top four teams can advance to the playoffs and Canada (3-3) currently sits fourth. The Canadians will play Argentina on Sunday in their final game of the second round.
"We just have to play the best that we can in the game," said head coach Jay Triano. "If we play, then we give ourselves a chance. If we don't play then obviously we don't.
"It's a must win for us and then we'll see what happens."
Tristan Thompson had 14 points and six rebounds for Canada, while Cory Joseph had 13 points and four assists.
James Feldeine led the Dominican Republic (4-2) with 20 points.
Canada jumped out to a quick start with a 28-18 advantage after the first quarter.
That lead evaporated in the second though, as the Canadians were outplayed by the Dominican Republic. The Carribbean nation took a 45-44 lead going into halftime despite Nicholson scoring 15 points in 17 minutes of the first half.
"We knew that we had a mismatch at the four spot, and we thought that we could get (Nicholson) the basketball," said Triano. "We saw last night (in Canada's loss to Venezuala) that if he doesn't score it's going to be tough for us to score points. We only had 59 points. We knew we needed to get him the ball."
The Domincans added just one point to its lead in the third, taking a 59-57 advantage into the final quarter.
Canada was not able to gain any ground on the Dominican Republic in the fourth quarter.
Canada has four NBA players on its roster for the tournament. Nicholson plays for the Orlando Magic, Joseph is with the San Antonio Spurs, Thompson is a member of the Cleveland Cavaliers and centre Joel Anthony is on the Miami Heat.
"We're here to learn about the international game," said Triano. "The players that we're playing are the youngest players in the tournament. That's why we're here, it's a long-term process."
The FIBA Americas Championship is a qualifying tournament for the 2014 FIBA Basketball World Cup in Spain.