Coach Brad Stevens elected to go to a smaller lineup, choosing not to play Zeller in 18 games, and when the 7-foot Zeller did manage to get in he hardly worked up a sweat, averaging just 4.4 points and 2.3 rebounds in only 8.8 minutes a night.
In Boston's 97-89 win over the New York Knicks on Tuesday at Madison Square Garden, Zeller posted a season-high 16 points and 10 rebounds in 26 minutes, the most he's played this season.
"I have been trying to work as hard as I can off the court and before the games," said Zeller of his preparation. "I did everything I could to stay out there.
"I made a couple of jump shots. It was nice to get back in the rhythm. I was trying to play loose and comfortable."
Zeller led a Boston bench that outscored New York's reserves 47-27. Backup shooting guard Evan Turner contributed 14 points and 10 rebounds and center Kelly Olynyk added 13 points off the bench.
Guard Isaiah Thomas scored 20 points and distributed eight assists to help the Celtics win for the sixth time in their last seven games.
Guard Arron Afflalo led the Knicks with 18 points, center Robin Lopez added 17 points and 13 rebounds and forward Carmelo Anthony recorded 16 points and 14 rebounds for his third straight double-double and 14th of the season.
The Knicks climbed to within 81-77 thanks to a 7-0 burst, but Turner and Zeller combined for 10 of Boston's next 12 points to help Boston move its lead to 93-83 with 3:22 to play. Zeller grabbed six rebounds in the fourth quarter and Olynyk added 11 points.
"He (Zeller) is a pro," said Stevens. "I have so much respect for him and in the same vein David (Lee) because of the way they go about it. It is great to see."
The score was tied on four occasions late in the third quarter before Boston outscored the Knicks 6-2 to close the quarter with a 70-65 advantage. New York committed five turnovers in the quarter and was just 5-of-19 from the field. Anthony was 2-of-7.
"They (Boston) have been a good defensive team all season," remarked Knicks coach Derek Fisher. "They force the most turnovers in the league. I don't think we were surprised by their ability to defend."
New York rookie forward Kristaps Porzingis struggled to score 10 points and get five rebounds, both below his season averages.
"We came out flat in the third quarter," said Fisher. "We couldn't get anything going and Kristaps played a lot of those minutes in the third quarter, so we got him out for a few minutes, got him in for a few minutes to start the fourth quarter and not much was happening for that connection in terms of those five guys that were out there.
"So it wasn't about Kris not doing good or bad, the five guys that were out there just weren't getting the job done."
Center Jared Sullinger started a 12-2 Celtics run with a layup that gave Boston a 59-53 lead with 7:54 to play in the third. Forward Jae Crowder (16 points) was responsible for five of those points.
New York held a 47-45 halftime lead behind 13 points from Afflalo.
The Celtics erased a 22-21 Knicks lead by going on an 8-0 run to start the second quarter.
Afflalo scored seven of the Knicks' points in a 9-0 run to start the game, then the Celtics went on a 9-0 run to tie it.
NOTES: Knicks F Kristaps Porzingis was named the Eastern Conference Rookie of the Month for January. It was the third straight month he claimed the award. Porzingis ranked fourth among all first-year players in scoring (15.3) and second in rebounding (7.2) in January. Porzingis posted four double-doubles and scored at least 12 points in 13 straight games from Jan. 3-26. ... Knicks G Jose Calderon missed his fourth straight game with a sore groin. ... Jae Crowder started at forward for Boston despite a bruised shin he suffered Sunday against Orlando.