Miami also noted veteran guard Dwyane Wade is doubtful with a hip injury.
Winslow has had to battle injuries early on in his NBA career. After playing in 78 games as a rookie, he appeared in a total of 86 games over the next two seasons. He was limited to 18 contests in 2016-17 due to a torn labrum in his right shoulder, and he was sidelined for 14 games last season due to a strained knee.
Now, the 22-year-old once again will have to hit the recovery trail.
When he has been healthy, Winslow has been productive and shown signs of improvement. He averaged 7.8 points per game last season while shooting 38 percent from beyond the arc. That's a strong jump from the 25.8 percent he shot in his first two seasons combined.
This season, he's averaging 12.7 points, 5.4 rebounds and 4.3 assists in 61 games. That comes on the heels of him signing a three-year, $39 million extension in October.
And while his line may not jump out on the stat sheet, Heat coach Erik Spoelstra has previously praised the fourth-year player for his overall impact rather than just what shows up in the box score. Winslow himself made it clear that he takes great pride in his defense.
"That's the part of my role that I really enjoy, trying to be that leader on the defensive end, to get guys going especially in some of the recent games and struggles that our first group has had," Winslow told Tom D'Angelo of the Palm Beach Post in January 2018.
Meanwhile, veteran teammates like Wade, who's played 58 games in his farewell season, and Udonis Haslem believe Winslow is on the verge of becoming the Heat's leader.
"I think that's going to be who he is," Wade said earlier this season, per the Miami Herald's Anthony Chiang. "I just think when you're 22 years old, you're just a little afraid to put yourself out there and get on a guy or this and that, or say something to a guy because you're so young."
Winslow may not be the team leader just yet, but his perimeter shooting and defensive presence will be missed should he be sidelined for any amount of time with his latest injury. His absence will also be a tough blow to the rotation as he had shown he could run the point as Goran Dragic dealt with knee issues.
Rodney McGruder, Derrick Jones Jr. and Dragic could all see added minutes Sunday with Winslow and likely Wade sidelined.