They will begin the playoffs Sunday with just 11 players in uniform, including four rookies.

Three players will be in the starting lineup for the first time in the playoffs and another will start a second game.

The short-handed Boston Celtics are going to gain experience on the fly when they face the Milwaukee Bucks in an opening-round series that gets going at the TD Garden. The 11 players have combined for 169 postseason games with Al Horford accounting for more than half of that total.

Horford has played 92 playoff games since entering the league in the 2007-08 season, but fellow starters Aron Baynes (26 games, one start), Terry Rozier (22 games off the bench), Jaylen Brown (17 games in a reserve role) and rookie Jayson Tatum lack that kind of experience.

The six reserves have played a combined 12 playoff games, led by Greg Monroe (six), Marcus Morris (four) and Shane Larkin (two). Rookies Semi Ojeleye, Abdel Nader and Guerschon Yabusele will debut.

With Kyrie Irving, Gordon Hayward, Marcus Smart and Daniel Theis out due to injuries, the Celtics have holes throughout the roster. Jabari Bird and Kadeem Allen are ineligible for the playoffs since they are on two-way contracts, and Jonathan Gibson, who finished the season with the Celtics, was signed too late to take part in the playoffs.

So it will be 11 players for Coach Brad Stevens with the hope Smart returns from his thumb injury late in the first round. Game 1 is at 1 p.m. Sunday, Game 2 on Tuesday night.

“This team, we’re resilient,” said Morris. “We all feel disrespected. (The injured players are) not here, so we have to approach the game like we’re going to win and go as far as we can. We have great coaches who are really good with us. We’re ready to go.

“I think we’re all much more prepared to handle everything we’re going through.”

The Celtics will lean on Horford’s experience. After that, it’s a learning process.

Baynes made one start for San Antonio. Rozier came off the bench the past two seasons while Brown got his feet wet as a rookie last year.

The Celtics have had to rely heavily on the 21-year-old Brown and 20-year-old Tatum this season, and that will be the case again with the lights shining in the postseason.

“It was amazing, eye-opening, the level of basketball, the intensity, how much every play matters,” said Brown, thinking back to last season.

Stevens has watched the two players, drafted No. 3 in back-to-back years, develop since October and is confident they can make an impact in the playoffs.

“I think Jayson can be a really good player right away (in the postseason),” said Stevens. “We don’t win the Washington series without Jaylen last year, and I thought Jaylen was really good in the Cleveland series.

“It’s amazing what young guys can do when they come into this league. Everybody will ask them, ‘Are you ready for the playoffs, are you ready for this, are you ready for that?’ They’re not playing baseball. They’ve been playing basketball their whole lives and they’re preparing for this moment all year. They’ll be ready.”