Preseason discussion about the Celtics focused on how a new-look squad would perform after the franchise opted to get beneath the second apron amid the uncertainty of Jayson Tatum’s return from a serious Achilles injury. Boston was expected to hover around a .500 record — many sports books had its over/under win total at 41.5 for the team — while it awaited the return of its superstar.

Three regular-season games have proved that its task is much more difficult in actuality.

The Celtics are 0-3 for the first time since 2013-14 — the first season of Brad Stevens’ head coaching tenure — as they approach a daunting second week of opponents. Only four iterations of the Celtics have begun a season with a 0-4 start, which has happened only once since the start of the century. The last time the Celtics commenced a campaign with a 0-5 mark was their inaugural season in 1946, the same year their home-opener was held at Boston Arena — now known as Matthews Arena — on Northeastern’s campus.

No Celtics team has ever lost its first six games or more.

Avoiding becoming the first squad to start a season 0-6 or worse will be difficult for the Celtics, who close a second half of a back-to-back Monday night at the New Orleans Pelicans. They will travel back home to Boston to face the Cavaliers before heading to Philadelphia on Friday and hosting the Rockets on Saturday. That marks seven games in the first 11 days of the NBA’s regular season.

Monday may be the Celtics’ best chance to evade their worst start in team history. Zion Williamson is listed as questionable with a bone contusion in his left foot. That could be a major break for the Celtics, whose small-ball lineup would likely struggle to contain a 6-foot-6, 284-pound Williamson. The Pelicans are the only upcoming Celtics opponent that is not favored to win against Boston, according to ESPN Analytics. Tip-off from New Orleans is scheduled for 8 p.m. with pregame action starting at 7:30 p.m. EST on 105.7 WROR.

After that? A win might be hard to come by.

At least three of Boston’s next four opponents provide a monumental advantage in length. The Cavaliers, who are expected to contend for the Eastern Conference’s spot in the NBA Finals, will deploy a starting frontcourt with three players who are 6-foot-7 or taller, including a 6-foot-11 Evan Mobley and a 6-foot-9 Jarrett Allen. The 76ers — even with an uncharacteristic performance from Joel Embiid at the TD Garden on Opening Night — just defeated the Celtics on their own floor a week earlier.

Perhaps the most difficult test will be the Rockets, whose shortest starter is a 6-foot-7 Amen Thompson. They have four starters who are 6-foot-11 or taller, including Kevin Durant at shooting guard. It is expected to be a major mismatch for the Celtics, who have only two players on their current active NBA roster standing 6-foot-11 or taller.

Rebounding issues mounting

Securing rebounds has been troublesome for the Celtics, who have been grabbing 39.0 boards per game — ranking 27th in the NBA — through their first three games. They have been out-rebounded in two of those three contests by 16 and 17 rebounds against the Knicks and Pistons, respectively.

Cleaning its offensive glass has been one of Boston’s worst categories by averaging 10.0 boards per game, tied for 22nd in the NBA. It is especially concerning due to its large volume of 3-point shooting. It’s taking 44.0 3-pointers per game — the third most attempts per outing — while hitting only 31.1 percent of its shots from deep, ranking 28th in the association. Failing to secure the ball after its long 3-point shots has sparked fast break opportunities for opponents, who are scoring 19.0 points in transitions.

Limiting long possessions has been a critical weakness for the Celtics, whose 29.0 defensive rebounding mark ranks 26th in the NBA and has allowed teams to score 24.7 second-chance points. Their limitation was most glaring during their match against the Pistons, who scored 32 second-chance points while grabbing 19 offensive rebounds.

New York Knicks center Karl-Anthony Towns (32) blocks a shot by Boston Celtics guard Payton Pritchard (11). (Vincent Carchietta-Imagn Images)Vincent Carchietta-Imagn Images

Head coach Joe Mazzulla has rarely used a double-big-man lineup, despite watching his team get out-rebounded consistently in the paint. Neemis Queta is leading the Celtics with 7.0 rebounds per game. Xavier Tillman’s 5.0 boards per game is the second most by a big man, with Chris Boucher and Luka Garza falling far behind with 3.0 and 1.5 rebounds, respectively. Tillman did not play in the Celtics’ 119-113 loss to Detroit, sitting on Mazzulla’s bench as a healthy scratch.

Perhaps what is most glaring about the Celtics’ rebounding struggles is that Payton Pritchard, whose 6-foot-1 frame often makes him the smallest man on the floor, is averaging 6.7 rebounds per game — the second-most of any Celtic. Jaylen Brown is just behind him with 5.3 boards.

Gonzalez making his impact known

Hugo Gonzalez made his NBA debut against the Knicks after sitting out of the Celtics’ season-opener against the 76ers. Gonzalez, who played 14.2 minutes per game in 29 appearances for Real Madrid last season, was the Celtics’ lone bright spot in their loss to New York, where he scored six points and grabbed four rebounds. Most of his production occurred in the fourth quarter of a 105-95 loss, playing in just shy of 11 of the final 12 minutes of game time.

His performance must have impressed Mazzulla, who inserted the Spainard product into the Celtics’ starting lineup at Detroit on Sunday. It was the first time Gonzalez had started in an NBA game, replacing Sam Hauser in Mazzulla’s lineup. He made his efforts known on the defensive end of the floor, posting two steals and forcing an offensive foul early in the first quarter before the Pistons ran away with the game. Gonzalez failed to generate much of an offensive game — going without a basketball or an assist — during his 18 minutes on the floor.