By Bongarts Getty/Getty Images
By Ed McGrogan

Four years ago, most people didn't know who Rafael Nadal was, Belgium had two women in the Top 10, and line calls couldn't be challenged through a machine. Plenty has changed – even Roger Federer, who had had an uninterrupted reign at No. 1 since then, will relinquish that spot in just a few days.

In a sport that changes by the week, it can be easy to forget what transpired just a few months ago, let alone four years. Here's a reminder of the notable performances at the 2004 Summer Olympics in Athens and what followed for the players who produced them:

Nicolas Massu (CHI)
Gold medalist – men’s singles and men’s doubles

THEN  
Track stars and swimmers are the athletes most likely to win gold in multiple events, but Massu pulled off the rare tennis double in Athens. He also covered much more ground then a few hundred meters. After requiring five sets to win doubles gold alongside Fernando Gonzalez, Massu came out the very next day and won singles gold in another five-set epic. He became the first man to accomplish this feat since Vincent Richards (USA) in 1924.

Winning both medals was the most significant individual achievement of Massu’s career, but the jubilation was shared, as they were Chile's first Olympic gold medals in any sport.

NOW    
Massu's performance at the Athens Games helped propel him into the Top 10 (No. 9) for the first time in his career, but he has been unable to sustain this level of play. Since then, Massu has steadily fallen in the world rankings, despite patches of good play. He reached five ATP Tour finals in the last four years, but won only one, at Costa do Sauípe in 2006. Injuries have also hampered Massu during this stretch. Currently, he is ranked No. 131, and has been competing in a mix of Challenger events and smaller ATP tournaments.

Fernando Gonzalez (CHI)
Gold medalist – men’s doubles
Bronze medalist –men’s singles

THEN  
Gonzalez's Olympic triumphs almost never came to pass, but in the most-pressure filled moments, the Chilean showed why he deserved them. Teaming with Massu against the German side of Nicolas Kiefer and Rainer Schüttler, the Chileans saved four match points and went on to win a five-set marathon, which ended near 3:00 am local time. Gonzalez's flair for the dramatics continued in his bronze medal match against Taylor Dent. In another test of endurance, Gonzalez once again saved multiple match points against Dent, winning 6-3, 2-6, 16-14.

NOW  
Gonzalez has achieved much since the 2004 Olympics, and continues to represent Chile admirably in this international sport. Using his booming forehand, one of the most renowned in men's tennis, Gonzalez has won six titles in the last four years, and has consistently been around the Top 20. His most celebrated achievement, however, was a runner-up finish at the 2007 Australian Open. Before succumbing to Federer in the final, Gonzalez went on a tear in Melbourne, defeating Lleyton Hewitt, James Blake, Rafael Nadal, and Tommy Haas. Haas felt the brunt of Gonzalez's fury - the Chilean hit 42 winners to just three unforced errors in a 91-minute semifinal slaughter.

Justine Henin (BEL)
Gold medalist – women’s singles

THEN  
Though she had spent most of the season sidelined with an energy-sapping virus, Justine Henin's performance at the 2004 Olympics was simply dominant. Henin (then Henin-Hardenne) was pushed to three sets only once in the tournament, but it required a comeback from 5-1 down in the third set against Anastasia Myskina, then the French Open champion.  Henin had an opportunity to serve out the semifinal match in the second set, but was broken and forced into a third. There, Myskina raced to a 5-1 lead, which appeared insurmountable after Henin lost all her momentum.

Amazingly, the Belgian clawed back to win the match 7-5, 5-7, 8-6, and then went on to defeat second-seeded Amelie Mauresmo for the gold with IOC president and compatriot Jacques Rogge watching in the stands.

NOW  
Henin's victory in Athens was just a prelude to further riches in the next few years. She won the French Open each of the next three seasons, the U.S. Open last year, and the WTA Tour Championships in 2006 and 2007. Her play earned her the world No. 1 ranking for over a year (April 2007 - May 2008). Of all the 2004 gold medalists, Henin was targeted as the most likely to repeat in Beijing. But we will never know, as she suddenly announced her retirement from tennis on May 14, 2008.

Ting Li & Tiantian Sun (CHN)
Gold medalists – women’s doubles

THEN  
China's first ever Olympic gold in tennis came in doubles, after Li and Sun ousted a number of teams boasting prestigious singles players. The eighth-seeded pairing ended Venus Williams' hopes of a doubles repeat early on, besting the American and partner Chanda Rubin in three sets. Notable WTA stars Francesca Schiavone and Alicia Molik also lost to Li and Sun as they progressed through the draw. The Chinese side squeezed out a tight semifinal match against the Argentinean tandem of Paola Suarez and Patricia Tarabini 6-2, 2-6, 9-7, then capped off their visit to Athens with a win against second-seeded Conchita Martinez and Virginia Ruano Pascual in the final.

NOW
Li and Sun combined forces after the Olympics, winning tournaments in Guangzhou, Estoril (both twice), and Pattaya City. But the partnership appears to be dissolved. Sun, who also has a singles title on her résumé, is currently teaming with compatriot Shaui Peng, and Li is now in the draw. But regardless of the pairings, the Chinese fans will be out in full support of the home teams.

Mardy Fish – USA
Silver medalist – men’s singles

NOW  
Andy Roddick was the American most expected to see in the Olympic finals, but after running into white-hot Fernando Gonzalez in the third round, Roddick's chances for gold crumbled. But the American mission kept on going, thanks to Mardy Fish. This American wasn't expected to get past the second round, but it was there that Fish upset fifth-seeded Juan Carlos Ferrero to start a surprise run. Fish's boosted confidence and aggressive play led him all the way to the finals, where he eventually fell to Massu - but not before beating Gonzalez in the semifinals, atoning for Roddick's loss and guaranteeing Fish a medal.

THEN  
Fish was the second-in-command American after winning silver, and got the  opportunity to play in the 2004 Davis Cup Final against Spain. But wrist surgeries took their toll on Fish, who soon relinquished this title to James  Blake. However, Mardy has been resilient, and unlike Taylor Dent, the American who finished fourth at the Athens Olympics, Fish has made a relatively successful comeback from injury. In 2006, Fish returned to the winner's circle in Houston, and also at two Challenger tournaments. This year, he made a shocking run to the finals of Indian Wells, where he toppled Roger Federer 6-2, 6-3 in the process.

Tomas Berdych – CZE
Upset Roger Federer in men’s singles

THEN  
Federer started his ascension to the summit of the tennis mountain in 2004, winning the Australian Open and his second consecutive Wimbledon title. Many thought the early rounds of the Olympics would simply be a formality for the Swiss but Berdych gave everyone a wake-up call after pulling off one of the biggest upsets of the year.

After beating Federer 4-6, 7-5, 7-5, Berdych, then just 18, was both overjoyed and stunned. "It's an unbelievable feeling," said Berdych. "Roger is the best player and he's winning every tournament (but) in the Olympics I had the chance and I beat him, so it's unbelievable." Berdych would win his next match against Tommy Robredo before losing in the quarterfinals to Taylor Dent. Still, Berdych's Olympics were a great success, and it appeared to be a springboard into a promising career.

NOW 
The Czech's progress since this milestone has been mixed. He won the Paris Masters in 2005, but has not won another tournament of great significance. In fact, he has won only one other title since then (2007 Gerry Weber Open). Berdych has often been labeled as an underachiever, but as an on-and-off Top 10 player, always remains a threat, especially on faster surfaces.