When you are rolling like the Celtics are, picking up road wins and turning November's mini-slump into a distant memory, there are few worries.
However, just as soon as Thursday's 90-83 win over the San Antonio Spurs was complete, there was a dark cloud on the horizon, a foreboding thought that turned the thrill of victory into the agony of defeat, or at least the desire to avoid it the next night.
Sure enough, that old NBA killer — the second half of a back-to-back — was an instant cause for concern as the Green faced the prospect of taking on a rested, youthful and athletic Oklahoma City Thunder squad roughly 21 hours later.
Throw in the fact that it will be the Celts' fourth game in six nights and it is almost a given that there will be some rough stretches.
"I'm sure they watched the game tonight," said Ray Allen of the Thunder, who have played just three games — all at home — in the last week. "It's a young team, the building is very energetic. We've got to go out there and pay attention to the game plan and make sure, you know, in the last game of the road trip, that we don't have any lulls."
Perhaps that is a cause for concern.
Although the Celtics led nearly throughout in taking care of the Spurs on Thursday, they did look a bit tired down the stretch.
In a seven-minute span of the fourth quarter, Boston saw a 12-point lead shrink to four. They were 2-of-8 with a handful of shots catching the front of the rim. And San Antonio made a killing on the offensive glass, often outhustling Boston underneath.
If it was an indication of the team's energy level as it nears the end of its first major road trip this season, then Oklahoma City could be in for a fun one.
Then again, the Thunder will be facing one of the few teams in the NBA that never seems too bothered by quick turnarounds.
The Celtics are 3-1 this season on the back end of back-to-back games and a remarkable 32-7 since the start of the 2007-08 season. Their 14-3 mark last season was better than everyone but the 66-win Cleveland Cavaliers.
While execution is key, as Allen alluded to, surviving such affairs sometimes takes a little chutzpah.
"[The Thunder have been] sitting and waiting and [have] young legs," said head coach Doc Rivers. "We're going to have to muster it up from somewhere. We spent some minutes tonight. It wasn't bad, but a couple of guys played some high minutes. We just got to get it from somewhere."
Rivers paused, the slightest look of road weariness on his face, and seemed to consider the raucous scene that often greets visitors at the Ford Center in Oklahoma City.
"They're not gonna get it from me," Rivers said.
If the team that dominated the Spurs for three quarters shows up, it won't need any help. But if the one that tired down the stretch shows up, the Celts can start to worry again.