Brooklyn Nets guard Jarrett Jack brings the ball up court...

Brooklyn Nets guard Jarrett Jack brings the ball up court against the Boston Celtics during the first half of an NBA preseason basketball game at Barclays Center on Wednesday, Oct. 14, 2015. Credit: Kathleen Malone-Van Dyke

The Nets' projected starting five hasn't had many opportunities to work together during game action so far this preseason and that didn't change in Wednesday night's 109-105 loss to the Celtics at the Barclays Center.

Jarrett Jack is partially to blame for that.

Although Shane Larkin started at point guard and Jack came off the bench because Nets coach Lionel Hollins still is evaluating certain combinations, Jack never got the opportunity to run with the other potential starters because he was ejected early in the second quarter for an excessive foul.

Frustrated he had the ball stolen from him by Jared Sullinger on a pick-and-roll near the free-throw line, Jack raced downcourt and basically threw his right shoulder into Jonas Jerebko, knocking the Celtics forward to the floor with 9:56 left in the half. After a video review by the officials and conferring with the league's replay center in Secaucus, New Jersey, Jack was assessed a flagrant-2 foul and was ejected.

It was another discouraging moment in what's been a rather pedestrian preseason for Jack. He turned the ball over seven times in his past two games and is 5-for-his-last-13 from the floor.

Jack, who knows Jerebko well, said his emotions simply got the best of him. Now, he will have to wait to see if the league slaps him with a one-game suspension and sits him down for the Oct. 28 regular-season opener against the Bulls.

"I hope not, but I didn't mean to do that actually," Jack said. "A little heat of the moment, a little bit more frustrated than anything and my intention wasn't to do that at all. But I thought the refs did make the proper call."

Jack started 27 games for the Nets last season, stepping in for a struggling Deron Williams. Entering this preseason, Hollins said Jack, Bojan Bogdanovic, Joe Johnson, Thaddeus Young and Brook Lopez were going to get the first crack at forming the Nets starting unit.

However, with the exception of a few minutes in the preseason opener, they have not all been on the floor at the same time. Bogdanovic missed a week while nursing a sore right ankle and that certainly didn't help, but Hollins also experimented with a different lineup at the game's outset in each of their initial four preseason contests.

Hollins still has two preseason games left -- the Nets host the 76ers on Sunday before closing their preseason schedule against the Celtics in Boston on Monday -- and said there will be other determinants in deciphering the opening quintet.

"It's not just the games," Hollins said.

"It's every day at practice. It's the whole process that suggests games are there, but it's through the whole thing. So that's how I will evaluate the whole who plays and who doesn't play."

"As I've said before, it's how the team fits -- each group what they bring, what kind of energy we have, what kind of consistency we have, because this is a big decision, when you decide who starts and who doesn't. So, I don't want to take it lightly."

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