The rookie forward is being provided pointers on what to expect in the playoffs from Brown, who was a first-year player last season.

Jim Fenton The Enterprise @JFenton_ent

WALTHAM – Jaylen Brown has been serving as a guide for Jayson Tatum since the Celtics reported for training camp last September.

 After going through his rookie season a year ago, Brown had plenty of tips for Tatum, who is in his first NBA season.

 That process has continued this weekend as Tatum gets ready for his first playoff game, which takes place Sunday afternoon when the Celtics face the Milwaukee Bucks at the TD Garden.

 Brown, who is 21, and Tatum, who turned 20 last month, represent the future for the Celtics after being picked No. 3 the past two years. But they have also been thrown into the middle of the team’s rotation this season, especially when injuries kept popping up.

 Brown averaged 14.5 points while Tatum was close behind at 13.9 points, shooting 43 percent from 3-point range. The Celtics are going to need that production to continue and increase in order to have success in the postseason.

 Tatum has been a poised rookie, but Brown has let him know the playoffs are a different atmosphere.

 “It’s different when you actually get to touch the stove (instead of) somebody telling you the stove is hot,’’ said Brown before practice Saturday afternoon.

 Brown played just 29 minutes in the opening-round six-game series with the Chicago Bulls last spring, but his time increased against the Washington Wizards and the Cleveland Cavaliers.

 Tatum said he has been told about the atmosphere and the increased intensity of the playoffs and appreciates having Brown next to him in the starting lineup.

 “It’s been great, especially with how we’ve both had to step up this season, just trying to play off each other,’’ said Tatum.

 Brown was saying early in training camp that Tatum was going to make an impact right away, and he was right.

 “Coming out of college and performing at this level is tough to do,’’ said Brown. “Jayson, I tip my hat to him and his work ethic.’’

 Coach Brad Stevens doesn’t think the bright lights of the playoffs will have a negative effect on Tatum.

 “He doesn’t get rattled,’’ said Stevens. “He can get knocked down and get back up. When you’re young, you’re put through a lot of challenges and he’s met every one of those and I don’t see any reason why he wouldn’t continue to play well.’’

 Brown and Tatum came a long way this season and are two reasons why a team that lost All-Stars Gordon Hayward and Kyrie Irving still managed to get 55 wins.

 “The NBA doesn’t have time to baby sit nobody, especially a 20, 19-year-old kid coming into the league on a playoff team,’’ said Brown. “I didn’t want give nobody no room (last season) to say, ‘He’s not ready,’’ or, “He has to mature.’ Everything is a growth experience.’’

Monroe faces ex-team: Greg Monroe spent two full seasons and played five games early this season with the Bucks, and now goes against his former team in the playoffs.

 “I see him really contributing,’’ said Al Horford. “He’s been waiting for this, to elevate his game. He knows this team really well. He was with them in the playoffs last year.’’

 The Bucks’ frontcourt includes Tyler Zeller, who played 193 games for the Celtics from 2014-17. Zeller was traded to Milwaukee by the Brooklyn Nets in February.

Number is 11: The Celtics open the playoffs with just 11 players, including four rookies. Stevens said his rotation will consist of eight or nine players, meaning rookies Abdel Nader and Guerschon Yabusele will not get much time.

 “Your guys who played the most minutes in the past are going to probably play a little more,’’ said Stevens. “That doesn’t change if you have 15 available or 11. We’ve had a couple of weeks now to work with this group as is. The good news is everybody’s going to be ready because who knows what curve balls are going to be thrown the rest of the way.’’