Wimbledon returns after being canceled last year due to the COVID-19 pandemic — the first time the tournament hadn't been held since there was no competition between 1940 and 1945 because of World War II. It was also the only major tennis tournament that wasn't held last year, as the French Open and U.S. Open were completed without fans.

And while the tournament is back — with plans for 50 percent capacity each day and full capacity for the finals — four of the sport's biggest names will be missing.

Naomi Osaka, the No. 2 ranked women's player, will miss the tournament to spend time with friends and family after withdrawing from the French Open amid disagreements with tournament organizers over media obligations. And on Friday, Simona Halep, the defending women's champion from 2019 and the No. 2 seed in the tournament, withdrew with a calf injury.

On the men's side, Rafael Nadal, the No. 3 ranked player, will miss the tournament to give his body time to heal after losing in the French Open semifinals to Novak Djokovic. And Dominic Thiem, who hasn't had success at Wimbledon but is ranked No. 5 in the world, is out with a wrist injury.

Those absences still leave the men's side with a clear dominant force in Novak Djokovic, the defending Wimbledon champion (who defeated Roger Federer in the longest final in tournament history in 2019). Djokovic is churning towards competing a calendar-year Grand Slam after wins at the Australian Open and French Open, and could even add an Olympic gold medal for a Golden Slam. Only Steffi Graf, in 1988, has achieved a Golden Slam.

But on the women's side, the quest for majors has never been more competitive. While Osaka has won four of the last 10 grand slam tournaments, five of those 10 were won by first-time champions. Of course, Serena Williams remains, seeded dangerously at No. 6.

Wimbledon begins at 5 a.m. Monday, with TV and streaming coverage on ESPN.

SIX PLAYERS TO WATCH

Novak Djokovic

Simply put, he cannot be stopped on a tennis court right now. Djokovic just beat Nadal at the French Open for the second time, which is more victories over Nadal at Roland Garros than all other men combined. He defeated Federer at Wimbledon in 2019 after staving off two championship points on Federer's serve. The World No. 1 has won four of the past six Wimbledon titles and seven of the past 11 men's majors. There is no other serious favorite on the men's side. With the Wimbledon title, Djokovic will tie Federer and Nadal's record of 20 career major singles championships.

Coco Gauff

She may not be a favorite to win the tournament yet, but if Gauff were to make a push, this could be the place. She made her breakthrough at Wimbledon in 2019 when she became the youngest player ever in the main draw and took the tennis world by storm after she reached the fourth round. Gauff, 17, just made her first major quarterfinal at the French Open, losing to the eventual champion Barbora Krejcikova. Gauff is currently ranked No. 23 in the world, her highest career ranking, and she is the No. 20 seed at the tournament.

Roger Federer

Federer, nearing his 40th birthday, is back at Wimbledon, where no one would blink if he made a push for his 21st major title at the tournament he has owned — and he is on the opposite side of the draw from Djokovic. But his return from a knee injury that sidelined him for most of the past 15 months has not been smooth, and he recently lost in the second round at Halle, a grass court warmup he has won 10 times. That came after he withdrew from the French Open after a grueling third-round victory. His eight Wimbledon singles titles are the most for a man and one short of Martina Navratilova's overall record of nine.

Serena Williams

The quest for Grand Slam title No. 24, which would tie Margaret Court's all-time mark, has been stuck at 23 since Williams won the Australian Open in 2017. She has played in four major finals since then, including at Wimbledon in 2018 and 2019, but the victory remains elusive. Williams reached the semifinals of the Australian Open in January, where she fell to Osaka, and was defeated by Elena Rybakina in the fourth round of the French. Wimbledon, where she is seeded sixth this year, is one of her best tournaments, with seven wins and a career 98-12 record.

Alexander Zverev

After years of inconsistency at the majors, Zverev is showing he can compete over five sets. He reached the U.S. Open final last year, where he lost a devastating five-setter to Thiem, and has followed that up with a quarterfinal appearance at the Australian Open and another five-set loss, to Stefanos Tsitsipas, in the semifinals at the French. The 24-year-old German, seeded fourth and away from Djokovic in the draw, has the talent, and at a tournament where the third-seeded Tsitsipas has played only six career matches and Thiem is out, he could get his chance to stand out.

Ashleigh Barty

The No. 1 ranked woman has struggled at Wimbledon over the course of her career — with a 5-4 record — but she did reach the fourth round in 2019. Barty has had a steady 2021 season, reaching the quarterfinals of the Australian Open and winning in Miami and Stuggart. But she retired in the second round of the French Open with a hip injury, and her health is one of the biggest question marks at Wimbledon.