Carlos Alcaraz will begin defending his Wimbledon men's title on Monday, with world number one Jannik Sinner emerging as his primary challenger instead of Novak Djokovic.

A win for the 21-year-old Spanish star would secure him back-to-back Grand Slam titles following his French Open victory, marking his fourth major championship.

Djokovic, a seven-time Wimbledon champion, is an injury doubt, as is Andy Murray, the 2013 and 2016 winner.

The era of the 'Big Four' in tennis is nearing its end:
- Roger Federer: Retired.
- Rafael Nadal: Skipping Wimbledon to prepare for the Olympics.
- Novak Djokovic: Recovering from knee surgery, may not compete.
- Andy Murray: Recovering from back surgery, uncertain to play.

This year's final could be the first in 22 years without any of these legendary players.

Djokovic, 37, who lost to Alcaraz in last year's final, has seen Sinner take his Australian Open title and had to withdraw from Roland Garros due to injury.

Alcaraz capitalized on this to win in Paris and is now set to defend his Wimbledon title.

"I will only play if I'm in a condition to compete for the title," Djokovic said, his knee heavily strapped during a recent training session in London.

Murray, also 37, recently had a cyst removed from his back and is now ranked 115th. He must decide by Friday if he will participate.

For the first time in 21 years, Federer, Nadal, or Djokovic didn't claim one of the first two Grand Slam titles of the year.

Jannik Sinner, the first Italian world number one at 22, won his first grass-court title in Halle, boosting his confidence for Wimbledon. Sinner, a semi-finalist in 2023, is ready to challenge Alcaraz.

American men have won the Wimbledon men's title 15 times in the Open era, though the last triumph was Pete Sampras's seventh title in 2000.

This year, four Americans are in the top 20:
- Tommy Paul: Won his first grass-court title at Queen's and is now ranked 12th.
- Taylor Fritz: Reached the 2022 Wimbledon quarter-finals.
- Sebastian Korda: Reached a career-high ranking of 20, made the semi-finals at Queen's, and aims to match his father Petr's 1998 Wimbledon quarter-final finish.

As Wimbledon begins, Carlos Alcaraz stands poised to defend his title against rising stars and a new generation of challengers.