“It’s just that we can only keep 23,” Claude Julien said an hour before Saturday night’s last preseason game against the Flyers.

Four days to first official face-off — Thursday in Columbus. And after a month of daily rosters reading like the first day of training camp because of the World Cup, it doth appear that Saturday night’s final preseason game against the Flyers showed what most of the 2016-17 Boston Bruins lineup will be on Causeway Street for the next six months.

Twenty-three players on each active game roster along with a few spares, and the Black and Gold likely comprise the following.

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Take Malcolm Subban out of the Saturday night roster, replace Anton Khudobin with Tuukka Rask and the goaltending is set. Rask played the entire game Saturday night, his first 60-minute affair in the 1-0 shutout win.

Add the healthy scratches of John-Michael Liles and Colin Miller on defense and the blue line takes shape as Liles, Miller, Kevan Miller, Zdeno Chara, Torey Krug, Adam McQuaid and one or both newcomers Rob O’Gara and/or Brandon Carlo.

Along with veteran Christian Ehrhoff.

The Bruins have a decision to make with Christian Ehrhoff, who came to camp on a PTO after representing Team Europe in the World Cup of Hockey. (Photo by Joe Makarski, Bruins Daily)

With Don Sweeney failing to make a splash on defense with a long-anticipated trade, the Bruins will rely on Ehrhoff, a one-time No. 1 or 2 defenseman, to regain his luster. After a successful showing in World Cup play for Team Europe, the 34-year-old German native has shown signs of a rebirth in Beantown with a goal and an assist in three preseason games. He came to Boston on a professional tryout after a rough go in LA last season where he had two goals, eight assists and a minus-10 in 40 games. He also comes at a bargain against the salary cap with an annual hit of roughly $900,000.

Carlo is the more likely to make the jump over O’Gara. Both, however, are a good bet to stay. Both are well over six feet and 200 pounds – and can move their feet. Carlo, a second-round pick in 2015 is more seasoned than O’Gara, whom Sweeney signed to a free-agent contract last spring after the stay-at-home D-man finished his last season at Yale in NCAA play.

Spending most of last season in Tri City (WHL), Carlo had 27 points in 59 games and added one point during a seven-game stint with Providence in the spring. The 6-5 defenseman is a coveted right-hand shot.

“I don’t think I have to put any added pressure on them,” Julien said before the game about the young guys. “We’ve got two young D’s [Carlo and O’Gara] tonight that again I don’t know where they’re going to start, but they’ve earned another look. They’ve lasted this long because the potential is there.”

“They were good,” he said after. “Early on they looked a little nervous; this was the biggest game they’ve been involved with. They got better and better as the game went on.”

“Overall, I couldn’t be more confident that I can play in this league; that I can grow in this league,” Carlo said after putting in 22:38 of ice time, second only to Chara’s 23:17. “Regardless what happens, it’s been a positive experience for me.”

Only Joe Morrow seems the interloper in that scenario. Scratched Saturday night, Morrow has been doing just that for the past two season, scratching his way on and off the roster, appearing in 33 NHL games last season and 15 in 2104-15.

Up front, the Bruins are knee-deep in center, so look for some pivots to move to the wing, starting Thursday night.

“You’re going to see a lot of line combinations [again],” Julien said.

Saturday night’s dressed forwards included Jimmy Hayes, Riley Nash, Dominic Moore, Patrice Bergeron, Matt Beleskey, David Backes, David Krejci, Ryan Spooner, Danton Heinen, Austin Czarnik, Brad Marchand, and David Pastrnak.

Noel Acciari and Seth Griffith were healthy scratches. Both appear to have won roster spots unless Brian Ferlin and/or Tyler Randell usurp fourth-line roles.

That’s a total of 14 with an average of 13 dressed for each regular-season game.

Backes was the big off-season free-agent signing to replace Loui Eriksson; Moore, the former Harvard captain and capable NHL journeyman, is in to fill the roles of Chris Kelley and Max Talbot.

It’s Czarnik and Heinen that may well be keys to a successful jump back to mid-April play. No doubt Boston needs added octane on the scoring sheet. And while this duo is a polar opposite in the size department, both have a short but impressive history on offense.

Czarnik is David Pastrnak size at 5-9 and 160. He put up 20 goals and 41 assists in 68 games last year in Providence with two goals and one assist in six preseason games.

He took a hit, however, early in the third period and was out the remainder, a likely concussion protocol that may derail making the opening night roster.

“It’s disappointing, Here’s a player that’s having a good camp and really playing well and he ends up with a hit like that,” Julien said.

Heinen tore up the NCAA the last two seasons with 45 and 48 points respectively his freshman and sophomore seasons at the University of Denver. At 6-1 and 195, Heinen is a developing package of power, one Sweeney and Julien need to play — and accept the growing pains. He had three goals in five preseason appearances.

With three goals in six preseason games, Danton Heinen made his case to appear on the Bruins roster for opening night. (Photo by Joe Makarski, Bruins Daily)

“If we need to make some changes or tweaks along the way, we can do those,” Julien said pregame.

Count on that as the 2016-17 season begins Thursday in Columbus.

Saturday’s outcome was Boston’s sixth one-goal difference in seven games — and fourth OT affair – with Ryan Spooner’s breakaway goal at 1:48 putting Boston’s the preseason slate at 4-2-1. Count on those dynamics for many finales in the 82-game schedule.