The Celtics headed out on this late-season road trip sparkling. A masterful win over the Warriors to extend a long winning streak only re-emphasized why they’re the heavy favorite to win a championship this June and end their 16-year title drought.

But while these Celtics remain the class of the NBA with the best record by a good margin, while they have shown for the majority of this season that they have the look and mentality to get over the hump, this week has been a reminder that there is certainly work left to be done.

Tuesday’s loss to the Cavaliers revealed the Celtics still have growth to do in crunch time. Two nights later, they were reminded that the details matter in order to beat a championship-level team. Jaylen Brown scored 41 points, and the Celtics nearly pulled off the impossible in a late comeback bid against the defending champs, but they ultimately weren’t sharp enough in a 115-109 loss to the Nuggets on Thursday night in Denver.

In a potential NBA Finals preview, the Celtics couldn’t get enough stops. Nikola Jokic had 32 points, 12 rebounds and 11 assists, and Jamal Murray added 19 points and eight assists as Denver’s dynamic duo were too much to overcome. Jayson Tatum, two nights after he fell short in the final moments of their loss to the Cavs, couldn’t respond. The Celtics couldn’t make up for it in other ways as they suffered back-to-back losses for the first time since November.

The Celtics trailed by 11 with 4:43 remaining but made a late rally that nearly resulted in a miraculous victory. Behind two clutch step-back 3-pointers from Jrue Holiday, the Celtics suddenly found themselves trailing by two in the final minute when Brown forced a steal of Murray, and put the C’s in transition. The ball eventually found Tatum wide open for a go-ahead 3-pointer from the corner, but it came up short.

On the next possession, Jokic found Aaron Gordon for an alley-oop dunk with 20 seconds to go, which ultimately sealed the Celtics’ fate.