The sign on the whiteboard in the Celtics’ locker room read: Pack For A Week.

That was the message Doc Rivers tried to impart after a crushing 98-79 loss for the team that can never do anything the easy way and will now have to do it the hardest way possible -- Game 7, on the road, against the best player in the world.

“They’re not just going to pack for [Saturday],” Rivers said. “They’re going to bring suits for Tuesday, and they’re going to bring suits for Thursday. And that’s the way we’re going to plan to do it.”

No one knows what’s going to happen in Game 7 on Saturday, just like no one knew what was coming in Game 6 on Thursday at the Garden and no one knew how it would go down in Game 5 on Tuesday in Miami. This series has defied all expectations and most rational thought, but in a game that LeBron James had to have, he delivered a masterful, all-encompassing performance with 45 points on 19-for-26 shooting and 15 rebounds in 45 minutes.

“I hope now you guys will stop talking about LeBron and that he doesn’t play in big games,” Rivers said. “He was pretty good tonight. Now that’s to bed. We can go ahead and play Game 7.”

James scored 14 points in the first quarter while the Celtics had just 16, and he was just getting warmed up. Fadeaways, fallaways, long jumpers, in the post, at the rim, James was unstoppable. Some of those looks they’ll give him all night. Some of them were far too easy. Their defense is specifically designed to stop great players, but there’s no adjustment for what LeBron threw at them.

“Listen, it’s one loss against tonight a great player against our defense,” Rivers said. “And I think our guys should take that very personal.” 

The Celtics? They were very stoppable. Credit the Heat with a nice adjustment defending Rajon Rondo and Kevin Garnett on their screen and roll. Credit Chris Bosh with finally being the big-man difference maker they haven’t had in the series. But cast a heavy hand of blame on the Celtics who managed to turn out off the juice on an electric atmosphere in the Garden before the first quarter was even finished.

They played in a hurry, but not fast. They forced shots instead of working through their sets. Paul Pierce turned in a Starks-ian performance – 4-for-18, 0-for-6 from 3-point range – and the bench contributed little. There were brief flashes of inspiration, mostly from Rondo, but they were quickly undone by careless turnovers and ill-advised fouls.

“Especially early on, I thought we tried to answer their shots,” Rivers said. “That’s what I meant by our offense. I just didn’t like it. Didn’t like the way we played offensively. First start with me. I have to get us some better stuff, but we have to trust the pass. We didn’t do that tonight at all. I thought we did a fabulous job in Miami in the fourth quarter of doing that, and for whatever reason tonight we didn’t.”

Late in the game, the chants started from the hearty few who remained to the bitter end.

Let’s Go Celtics. Let’s Go Celtics.

“Kevin was sitting next to me, and I said these are â€‘‑ I know I’m biased, but they’re the best fans I’ve ever played in front of or ever seen in my life,” Ray Allen said. “They understand the situation that is before us, and we understand it. That was basically them sending us off, letting us know, hey, this is still well and alive. We need you guys to go down there and get a win for us. We all felt it on the bench.”

They kept it up through the garbage time minutes and the stoppages. They kept it going through the free throws until the entire bench was standing and applauding the fans right back. Was it a sendoff for the ultimate game of fate, or a farewell to an amazingly improbable five-year run that has seen them defy the odds and their own mortality time and again?

“I want to say to all the fans, thank you guys. I’ve never in my life experienced anything like this -- in any sport,” Garnett said. “I’m just truly blessed to be a Celtic and be a part of the city of Boston. That’s what’s up to all the New Englanders around here. It’s [bleeping] crazy.”    

Bleeping crazy is a pretty good description of what they can expect back in Miami. You’d have to be a little bit nuts to think this team can unpack those suits for the NBA finals in Oklahoma City next week, but this is the Celtics and this is their way. If you don’t believe in crazy, you haven’t been following this team all season.

This will be their seventh Game 7 in this era and while they have an admirable 4-2 record in knockout games, six of them have come at home and they have yet to pull off the ultimate escape on the road. It would be just the thing for this team to accomplish, but it will be difficult. They let the game’s best player off the mat and let an amazing chance slip through their grasp.

“Honestly, that was a great opportunity, but we have another opportunity,” Rivers said.  “We get to play another game, Game 7. I would say most of the people in this room would have said, ‘Wow, they’re going to get to Game 7. We’ll take it.’ That’s the way we have to view it. We won a game at their [arena], they won here. Now we get to play for all the marbles. This team has not done it the easy way this year. Maybe this is justified for us. Go in there and do it.”