BOSTON — Payton Pritchard scored 28 points off the bench, powering the Celtics to a 134-99 victory over the Chicago Bulls on Monday at TD Garden. Boston improved to 2-1 with its first lopsided win of the season, getting its biggest scoring contribution from Pritchard and a decisive advantage in the third quarter.

Pritchard scored 19 in that period, when Boston outscored Chicago 39-21, according to Boston.com. Jayson Tatum added 23 points, seven rebounds and six assists, while Paul George finished with 16 points. The Celtics’ final margin was 35 points.

The defining stretch came near the end of the third. Pritchard connected on three consecutive 3-pointers during the period’s final two minutes, a sequence that brought the Garden crowd to its feet, MassLive reported. Those nine points were part of a quarter in which he nearly matched Chicago’s entire scoring output by himself.

A third-quarter separation

Boston gained 18 points on Chicago during the third quarter alone. That accounted for more than half of the eventual winning margin and gave the Celtics a substantial scoring edge in the period that featured Pritchard’s most productive stretch.

His 19 points represented nearly half of Boston’s third-quarter total and more than two-thirds of his own scoring for the game. Chicago managed just two more points as a team during the quarter than Pritchard produced individually, underscoring the size of his contribution to the separation.

The late run of 3-pointers supplied nine of those 19 points. It was the most concentrated scoring sequence described in the game reports, with three successful shots from beyond the arc arriving in the closing minutes of an already productive period for Boston.

Support beyond the bench

Pritchard was Boston’s leading scorer, but the Celtics also received a combined 39 points from Tatum and George. Together, the three players accounted for 67 points — exactly half of the team’s total in the victory.

Tatum finished five points behind Pritchard while also contributing on the boards and as a passer. His seven rebounds and six assists accompanied the 23-point performance, giving Boston production beyond the scoring supplied by its reserve guard.

George’s 16 points added another contribution alongside the two players who cleared 20. Boston.com reported all three scoring totals, while MassLive’s coverage highlighted Pritchard’s work off the bench and the Celtics’ first blowout of the young season.

The result moved Boston above .500 through three games. The 134-point team performance and 35-point margin marked a clear departure in scale from the club’s earlier results, with MassLive identifying Monday’s game as its first runaway victory.

For this win, the central difference was concentrated in one quarter: Boston scored 39, Chicago scored 21, and Pritchard supplied 19 of the Celtics’ points before finishing with 28 for the night.