The Celtics’ preseason is nearly complete, finishing with one final exhibition matchup in Toronto on Tuesday. Opening night against the New York Knicks – and the accompanying banner-raising/ring ceremony – will follow one week later.

With nearly every player from last season’s championship team still on the roster, there isn’t much we don’t know about Boston’s 2024-25 squad, outside of whether it has what it takes to become the NBA’s first repeat champion in six years.

But there are a few lingering questions as the Celtics gear up for their title defense.

1. What’s Al Horford’s role?

The only Celtics players who haven’t seen the floor this preseason are rehabbing center Kristaps Porzingis, who’s set to miss at least the first month of the regular season as he recovers from leg surgery, and his top backup, Horford.

Head coach Joe Mazzulla has said the 38-year-old big man isn’t injured but simply “ramping up” ahead of his 18th NBA season, and that he will play Tuesday against the Raptors. But his usage thus far has raised questions about how exactly Mazzulla plans to deploy his most experienced player this season.

Horford surely won’t see the same workload he had in the 2024 playoffs, when he started the final 15 games following Porzingis’ initial injury and averaged north of 30 minutes a night. He hasn’t played the second night of back-to-backs in several years and will need his minutes managed to avoid gassing him out early in the season.

Could Mazzulla choose to bring Horford off the bench even without Porzingis available? He hasn’t ruled that out, and understudy Luke Kornet has played well with Boston’s top unit this preseason, most recently pouring in 15 first-half points Saturday in a 50-point win over a shorthanded 76ers team.

“He’s worked really hard this summer, and I’ve definitely seen him get better,” Mazzulla said of Kornet, who’s coming off his best pro season.

Xavier Tillman (more on him below) and Neemias Queta also will factor into the Celtics’ plan to replace Porzingis.

2. Is Jordan Walsh a rotation player now?

After a forgettable rookie season mostly spent in Maine and a rough showing at the Las Vegas Summer League, Walsh has been a pleasant surprise this preseason.

Last year’s second-round draft pick looks more comfortable, is shooting the ball more efficiently (48.1% field-goal percentage; 37.5% from three) and has held up well as a defender and rebounder. Against Toronto on Sunday, he turned in a 16-point, 10-rebound double-double, starting and playing 30 minutes while Boston rested its regulars.

Walsh also was part of the Celtics’ second unit for both of their games in Abu Dhabi, seeing ample playing time with core reserves like Payton Pritchard and Sam Hauser.

“Just having an understanding of what his job is: defend at a high level, defend multiple positions, rebound and then make reads on the offensive end. So he’s doing a great job,” Mazzulla said. “Just really proud of his growth. … (He’s) starting to carve out a role and just a really good attitude towards it. So it’s been fun to watch him grow.”

Walsh won’t leapfrog any returning player on Boston’s loaded depth chart, but Oshae Brissett’s offseason departure freed up a spot at the end of the rotation. So far, Walsh – who, at 20 years old, still is the youngest player on even the expanded preseason roster – looks like the favorite to inherit those minutes.

3. Will Lonnie Walker IV make the team?

In all likelihood, probably not. Walker is on an Exhibit 10 contract – essentially a training camp tryout deal – and because the Celtics are well above the NBA’s luxury tax threshold, permanently signing him to the roster would cost close to $10 million in tax penalties, even with a veteran-minimum salary. Leaving their final 15-man roster spot vacant is the more likely path for Brad Stevens and Co.

That said, Walker has played well in the last two games after seeing minimal playing time in Abu Dhabi. The 25-year-old wing had nine points (4-for-7), seven assists, four rebounds, two steals and a block in 25 minutes off the bench Saturday. Then he started and put up 20 points on 8-of-15 shooting on Sunday, scoring from the perimeter and with creative finishes around the basket.

Mazzulla said Walker has been “really good” since his arrival, praising his patience and willingness to learn despite his less-than-desirable contract situation.

“I saw some things from him (Saturday) that he might not think are important, or other people won’t, but they’re really, really important things, defensively and then offensively,” the coach said. “Whether it was his positioning or whether it was a small cut that he made or a read that he made, those things go a long way because they open up opportunities.”

The Celtics’ financial restrictions could push the seventh-year veteran into the G League – where he hasn’t played since his rookie season in 2018-19 – but he’ll have one last chance to prove his worth Tuesday night.

4. Is Xavier Tillman’s 3-point improvement sustainable?

Though he drilled a memorable clutch three in Game 3 of the NBA Finals, outside shooting never was a strength for Tillman, who joined the Celtics ahead of last season’s trade deadline. Over his four NBA seasons, the 6-foot-8 big has made just 26.7% of his threes while attempting fewer than one per game.

That’s changed over the last few weeks. In three appearances this preseason, Tillman is shooting a remarkable 80% (6-for-8) from beyond the arc, showcasing a previously dormant aspect of his skill set. He can’t expect a success rate anywhere near that high over the course of a full season, but even bumping his 3-point percentage up to the mid-30s would represent a major improvement – and an important one for Boston as it tries to replace Porzingis’ rare blend of rim protection and perimeter shooting.

“He’s just doing a great job being decisive,” Mazzulla said. “His shot selection and his spacing and his pick-and-roll reads – he’s worked really hard in the offseason just becoming more versatile, and the player development team has worked really hard on that, and it’s a credit to them. He’s playing really well, and I really like the time he’s putting into it.”

It was notable that Tillman sat out Sunday night’s win along with Kornet and the Celtics’ starters. Expect him to have a significant role to start the season.