MIAMI - Chris Bosh returned from a nine-game injury lay-off but he could not help the Miami Heat from falling to a surprise 94-90 home loss to the Boston Celtics that leaves their season on the line.
The Celtics now lead the series 3-2 and a win in Game Six in Boston on Thursday would book their place in the NBA Finals.
For the Heat, the equation is brutally simple - win or else the second season of the 'Big Three' era will end in under-achievement.
"It is going to be an extremely difficult time but that's what the playoffs are about," Bosh told reporters, when asked about the coming two days of preparation for the game.
"In order to get to where we want to go, we're going to have to face huge challenges and I think we are in the biggest challenge of our lives right now, of our professional careers.
"We have to overcome it. It is going to be very, very difficult but that's how it is supposed to be," he said.
Another member of Miami's 'Big Three', Dwyane Wade, was under no illusions about the magnitude of the task facing the Heat in Boston but was sure they can get out of the hole they find themselves in.
"We normally respond really well to desperation. We are a confident team, we haven't won much in that arena but we won one last year that gives us the confidence that we can go up there and get the win," Wade said.
"But we have to play a great game, as close to perfection as possible.
"At this point, it is not about schemes or about play-calling it is about 'mano a mano' and see who comes out in the next game and wants it the most".
Heat coach Erik Spoelstra saw the series in boxing terms.
"You have to go back to your corner right now. We all just have to huddle up and lean on each other. We're the only people we can depend on right now and that can be a powerful thing.
"All we have to do is focus on winning Game Six, then all of a sudden, bang, that momentum changes again," he said.
Bosh's return from an abdominal strain gives Miami more options even though on Tuesday he was not yet ready to join the starting rotation.
Bosh played for 14:23 minutes and put up nine points and seven rebounds but he did not feature down the stretch as the game moved away from Miami.
Spoelstra said he had considered putting Bosh back into the action but felt that might have been too risky.
"I didn't think it would necessarily be fair to him to throw him in with three minutes to go. But he gave us some good minutes and that is something we can build on. I didn't see a great deal of rust," he said.
Bosh said he would be able to offer more to the team on Thursday.
"I definitely have more to give and I will be there. I'll be ready to play more than I played tonight," he said. (Reporting By Simon Evans. Editing by Patrick Johnston)