A quarter of the 21st century has passed, during which tennis has seen rapid expansion. This development is inseparable from the joint efforts of four players.
Who are these four? They are the four players with over 20 Grand Slam singles titles—Serena Williams along with the trio of Federer, Nadal, and Djokovic—who have stayed atop the rankings for years and have each completed career Grand Slams multiple times.

Recently, Sports Illustrated released a new ranking titled "Top 25 Tennis Players of the Last 25 Years of the 21st Century." Besides these four giants, who else ranks among the top? I will elaborate on the other 21 players over several articles.

[25] Andy Roddick
Although American men still make up a significant portion of the top 30, the last American male to win a Grand Slam singles title remains Roddick. The American Cannon is still active in tennis-related circles today.
He was one of the most consistent players on the ATP Tour in the 2000s. He peaked in 2003 by winning the US Open and finishing as both the world number one and year-end number one. He stayed in the world top ten for nine consecutive years. Unfortunately, he reached four Grand Slam finals but lost them all to Federer—three at Wimbledon and one at the US Open.

[24] Daniil Medvedev
Among the generation between the old giants and the twin stars, Medvedev stands out for both personality and achievements. He is the only player from this period to reach world number one. His main accomplishments include one US Open title, five Grand Slam finals (all lost to the big stars), and one year-end finals championship. Interestingly, his 21 career titles come from 21 different tournaments.
[23] Simona Halep
Giving up what many women cherish most for tennis shows just how determined this Romanian girl is! She has been a consistently high-ranked player, staying in the world top ten for seven straight years and winning back-to-back titles: the 2018 French Open and 2019 Wimbledon. Without the doping controversy, she might have had an even more brilliant career.
[22] Angelique Kerber
The German has been a steady presence in the world top ten for many years. Her breakthrough came in 2016 with Australian Open and US Open titles and an Olympic silver medal in Rio. Two years later, she defeated the dominant Serena Williams to win Wimbledon, coming just one French Open away from completing a career Grand Slam.
[21] Jennifer Capriati
More active in the 1990s, this player experienced major ups and downs both on and off the court throughout that decade. Triumph followed adversity! She won her first Grand Slam at the 2001 Australian Open, accumulating three Grand Slam singles titles in total, reached world number one, and was inducted into the Hall of Fame. The top American female was unmatched!

[20] Stan Wawrinka
Breaking through the dominance of the big four and winning a Grand Slam is already remarkable, but Wawrinka captured three, all by defeating the giants in finals. This legendary feat is truly inspiring!
Within three years, Wawrinka won the Australian Open, French Open, and US Open. Although achieving a career Grand Slam is nearly impossible, these three titles have secured his place in history.(Source: Tennis Home, Author: Luo Cheng Qiye)