Jordan Walsh’s best performance of the summer ended before halftime.

The third-year Celtics forward was ejected from Monday night’s Summer League matchup with the Miami Heat in Las Vegas after picking up two technical fouls in quick succession.

The first came after Walsh drew a foul in transition on a tough make against Erik Stevenson. Walsh bumped Stevenson while celebrating the and-one bucket, and the Miami guard shoved him in response, resulting in technicals for both players.

Seven seconds later, Walsh made contact with Pelle Larsson near halfcourt, then pushed the Heat wing into the front row of seats. When Larsson turned to accost him, Walsh shoved him again, then screamed as the two were separated.

The reckless play and ensuing scrum resulted in another set of double technical fouls on Walsh and Larsson. Since the tech was Walsh’s second, he was booted from the game with 3:34 remaining in the first half.

Before his early exit, Walsh scored 13 points on efficient 5-of-8 shooting and added three rebounds and one steal in 10 minutes of action. It was shaping up to be an encouraging bounce-back performance by the 2023 second-round draft pick, who was whistled for seven personal fouls and went 2-for-10 from the field in Sunday’s win over the New York Knicks.

Walsh opened Summer League with a strong 17-point outing (on 6-of-12 shooting) last Friday in a victory over the Memphis Grizzlies. He’s the longest-tenured Celtic on the team’s summer squad and is looking to prove he deserves a rotation role in Year 3 after logging 7.8 minutes per game across 52 appearances last season.

In his two-year NBA career, Walsh has averaged 1.6 points and 1.5 rebounds per game (7.2 and 6.2 per 36 minutes) while shooting 36.7% from the field and 26.6% from 3-point range. He has yet to crack head coach Joe Mazzulla’s core rotation, but there will be opportunities for Celtics reserves to earn additional playing time after the team lost nearly half of its regulars this offseason, including rehabbing superstar Jayson Tatum (Achilles, out indefinitely). It’ll be up to players like Walsh and fellow Summer Leaguer Baylor Scheierman to seize those chances.

Boston wants Walsh — who, at 21, still is one of the team’s youngest players — to be aggressive at both ends of the floor, but his lack of composure Monday night likely won’t sit well with the Celtics’ shot-callers, many of whom had a literal front-row seat to his ejection.

The group of spectators he pushed Larsson into included Celtics president of basketball operations Brad Stevens, team president Rich Gotham, vice president of basketball ops Mike Zarren and incoming majority owner Bill Chisholm.

The Celtics have at least two games remaining on their Summer League schedule. They’ll face the Los Angeles Lakers on Thursday at 9 p.m. ET.