Suni Lee is back in the spotlight.

The reigning Olympic all-around champion returns to competition at this weekend's Winter Cup for the first time since last year's national championships. Lee had to skip the world team selection camp last fall because of a kidney condition that limited her training. She's only been able to train full time for about a month, longtime coach Jess Graba told Olympics.com.

The Paris Games are still a long way off. But Lee is one of the world's most captivating gymnasts when she's healthy, and Winter Cup is the first chance to see what kind of form she's in. Here’s all you need to know:

What is the Winter Cup? Why does it matter?

Winter Cup serves as both a qualifier for the national championships and, for the men, a selection meet for the national team. The U.S. championships are the first step in the Olympic selection process. There are a few exceptions, but you have to compete at nationals in order to get a spot at Olympic trials.

Is Simone Biles competing in the Winter Cup?

Simone Biles won't be competing at Winter Cup. She's already qualified for this year's national championships as a member of the team for last year's world championships, where Biles won, well, just about everything.

OPINION:Simone Biles wins something more important than medals at world championships

After leading the U.S. women to the team gold, Biles won her sixth all-around title and golds on floor exercise and balance beam. She also was the silver medalist on vault. The five medals give her 37 at the world championships and Olympics, making her the most-decorated gymnast of all time, male or female. Biles is likely to begin her competitive season in mid-May, at the U.S. Classic.

What happened to Gabby Douglas?

Gabby Douglas, the 2012 Olympic champion, was to return to competition for the first time in almost eight years at Winter Cup. But she announced Thursday afternoon that she's tested positive for COVID and won't be able to compete.

"I was so excited to get back out on the competition floor, but unfortunately, I just tested positive for COVID :(," Douglas wrote in part in an Instagram post. "... I'm crushed but I'll see you guys soon!"

More:Gabby Douglas, who hasn't competed since Rio Olympics, out of Winter Cup with COVID

In order to compete at nationals, Douglas still has options. She can go to a selection camp April 1-4. She also could do the American Classic, April 25-28, or the U.S. Classic, May 17-19.

How can I watch the Winter Cup 2024?

All events can be watched on USA Gymnastics' YouTube channel.

Winter Cup 2024 schedule

The women’s competition is Saturday, from 1 to 3:30 p.m. ET. The first day of the men’s meet is Friday, from 1:30 to 4 p.m., and it wraps up Sunday, from 5:30 to 8 p.m. The complete schedule, including junior events, is here.

Winter Cup gymnastics lineup: Who to keep an eye on

Lee's presence gives Winter Cup some serious star power. She's the reigning Olympic champion, and dazzled during her NCAA career at Auburn. Skye Blakely, a member of the United States’ gold medal-winning team at the last two world championships, also plans to compete. So does Kayla DiCello, the all-around champion at the Pan American Games last fall.

Katelyn Jong and Tiana Sumanasekera, who were in the top 10 at last year’s national championships, are in the field, as is Hezly Rivera, last year’s U.S. junior champion.

For the men, all eyes will be on Brody Malone, the two-time U.S. champion who has not competed since injuring his knee on high bar during the DTB Pokal Team Challenge in March 2023. Malone tore his meniscus and two ligaments, and also had a tibial plateau fracture.

Malone will only do pommel horse, still rings, parallel bars and high bar at Winter Cup as he works his way back to full fitness. But he says he plans to do all six events at nationals and Olympic trials.

"It feels pretty good, so the plan is to be back doing floor and vault by (nationals)," Malone said Thursday. "That's the goal."

What is the Winter Cup format? How does it work?

For the senior women, Winter Cup is a one-day meet on Saturday afternoon. Gymnasts can choose to do the all-around, or compete on two or three events. Lee plans to do uneven bars and beam, and she'll need to score 26.40 or higher to qualify for nationals, which are May 30 to June 2 in Fort Worth, Texas.

For the senior men, Winter Cup is a two-day competition, on Friday and Sunday. A national team will be named at the end of the event, and those gymnasts are qualified for the U.S. championships. There’s also a points list that will be updated after Winter Cup, but it’s confusing and, with several other events between now and nationals, is best not worried about until later.

For both the men and the women, results at Winter Cup also will help determine assignments for international meets this spring.

What else to watch this weekend? The Nastia Liukin Cup

There are also three lower-level meets. There’s a Winter Cup for the junior women, an Elite Team Cup for junior men, and the Nastia Liukin Cup for Level-10 gymnasts, which is the last level before they go elite.