LAKE BUENA VISTA, Fla. -- As the Boston Celtics were still coming to grips with the news that Gordon Hayward will be out until at least the Eastern Conference finals with a sprained right ankle, Celtics coach Brad Stevens wasn't ready to commit to how his team would adjust to his absence moving forward.

"I think we can certainly do a lot here but all that is stuff is to be determined," Stevens said after the Celtics practiced inside the NBA's bubble at the Walt Disney World Resort Tuesday afternoon. "We haven't gotten into that stuff or that conversation."

Hayward was diagnosed with a Grade 3 right ankle sprain on Tuesday and is expected to miss four weeks. The forward, who is averaging 17.5 points, 6.7 rebounds and 4.1 assists for the season, suffered the injury in Monday's 109-101 victory over the Philadelphia 76ers.

"He's bummed, as you can imagine," Stevens said. " [He's] put in a lot of time and effort, and you do so for this time, for the playoffs. That's what we all look forward to, and we've been really lucky thus far in the bubble to have good health and, of course, [after] Game 1 we don't.

"But that's part of it. We've lived this before and we're going to have to have other people step up. That's why you have a team."

One change doesn't need to be spelled out, as super sub Marcus Smart is all but certain to slide into Hayward's vacated place inside Boston's starting lineup. Where the questions will begin is what happens to make up for the 35 or so minutes each game that Hayward was going to play as part of Boston's rotation.

The Celtics entered the postseason with their five elite perimeter players -- Hayward, Smart Kemba Walker, Jaylen Brown and Jayson Tatum -- all expected to shoulder massive minutes loads, with Boston's limited depth behind them to then get a few minutes here and there to give them a breather.

That's precisely how Game 1 shook out, with those five guys being the only Celtics to play over 30 minutes, and -- other than Daniel Theis playing 25 -- the only ones to even play more than 15. While Smart, Brown and Tatum, in particular, will likely play even more minutes going forward (they played 32, 39 and 41 minutes, respectively, in Game 1) there will still be a need for other players on the Celtics to pick up some of the slack.

"We have a deep rotation, a deep bench, so whoever is going to step up, we know we are going to trust our whole team," said Theis. "So guys are going to get their opportunities, get their minutes, and everybody has got to be ready."

The question Stevens will have to answer between now and Game 2 on Wednesday night is which players will get those opportunities. Rookie Grant Williams got a couple of fourth quarter minutes in Game 1, and played well. Backup point guard Brad Wanamaker, a veteran Stevens has grown to trust, seems likely to get a bump up from his 10 minutes he played in Game 1, while another rookie, Romeo Langford, and veteran Semi Ojeleye also could get a crack at rotation minutes.

No matter what Stevens does, he'll be choosing from a collection of players who have limited playoff experience. Still, Smart said he has full confidence in the teams' young players to step up and perform in Hayward's absence.

"Tremendous confidence," Smart said, in their ability to step up. "We're doing everything we can as the older guys, the guys that's been here, to really get those guys ready on what to look for and what to expect when they get in the game. Just be ready and not get caught by surprise.

"The way they've been handling it, the way that they've been preparing has been very professional and we applaud them for it. We know they're not going to be perfect just like we're not going to be perfect, but as long as we are on the same page and playing hard and communicating out there, we think we'll be all right."

As for Philadelphia, Hayward's absence could force a lineup change for the Sixers. With Ben Simmons out of the lineup, Philadelphia already was in a difficult situation, having to start former Celtic Al Horford at power forward -- where he had to try to scramble to guard Brown offensively, and struggled to take advantage of that matchup defensively.

After practice Tuesday, Sixers coach Brett Brown again hinted -- as he did before Game 1 -- that he could be leaning toward a change to his starting lineup to better adjust to facing the smaller, quicker perimeter players for the Celtics, who spent all of Game 1 hounding Philadelphia's guards and preventing them from making easy passes inside to star center Joel Embiid in the post.

"At this point, it's all on the table," Brown said. "It's all on the table.

"... I thought Matisse [Thybulle] did a great job, I thought [Josh Richardson] was J-Rich, and we need them to be elite defensively on those two great scorers [Walker and Tatum] . So, anything's on the table once we've learned this Gordon Hayward news."