Osaka's return among major storylines entering 2024 Aussie Open

The world's top tennis players have descended on Australia to compete for the season's first major.

Last year's tournament saw Novak Djokovic continue his dominance Down Under, while Aryna Sabalenka took home her maiden Grand Slam singles trophy.

Here are five storylines to watch when the action begins in Melbourne.

Djokovic begins elusive pursuit

Few things have evaded Djokovic during his illustrious career. The World No. 1 has won a record 24 major singles titles, 40 Masters 1000 crowns, seven year-end ATP Finals, and led his native Serbia to a Davis Cup championship. But the one omission from his staggering list of accomplishments is a calendar-year Grand Slam.

Only three players have captured all four major singles titles in one year since the start of the Open era. Rod Laver was the last man to sweep the Grand Slams, doing so in 1969. Meanwhile, Steffi Graf is the most recent player to replicate the feat, completing the calendar-year Grand Slam in 1988.

Djokovic has come agonizingly close to joining the two legends, falling a win short in three different campaigns. In 2015, he was upset by Stan Wawrinka in the French Open final. Six years later, Djokovic went unbeaten at majors until his loss to Daniil Medvedev in the championship match at Flushing Meadows. Djokovic's pursuit of history was halted once again in 2023, as Carlos Alcaraz got the best of him in a five-set thriller at the All England Club.

Djokovic's legacy is already solidified, regardless of whether he's the last man standing at each major this season. Still, the 36-year-old has his eyes set on all four Grand Slam trophies as well as an Olympic gold medal.

"Well, you can win four slams and an Olympic gold," Djokovic told reporters after defeating Jannik Sinner in last year's ATP Finals championship match. "I have always the highest ambitions and goals. That's not going to be different for the next year.

"The drive that I have is still there. My body has been serving me well, listening to me well. I have a great team of people around me. Motivation, especially for the biggest tournaments in sport, is still present. It still inspires me to keep going."

New moms, former champs return

Naomi Osaka and Angelique Kerber are both back on the Grand Slam stage after going on maternity leave last season. Both have previously triumphed at Melbourne Park and could be dangerous early opponents for any seeded player.

Osaka's booming serve and power from the baseline have made her lethal on hard courts. All seven of her titles have come on that surface, including the 2019 and 2021 editions of the Australian Open. Before the campaign, Osaka reunited with coach Wim Fissette, who guided the Japanese superstar to her most recent pair of major crowns. Osaka reached the second round at last week's Brisbane International, tallying 14 aces and winning 81% of her first-serve points in a tight three-set loss to former World No. 1 Karolina Pliskova.

Meanwhile, Kerber made her 2024 debut at the United Cup. Like Osaka, the three-time Grand Slam champion is working with one of her former coaches, rejoining forces with Torben Beltz in her comeback. The initial results haven't been great, as Kerber dropped four of five matches in the 18-nation team competition. However, she showed flashes of her prime form. The 35-year-old's trademark defensive hustle was on display in her lone victory over Ajla Tomljanovic, and she didn't make an unforced error in a 6-1 opening-set win against World No. 20 Caroline Garcia.

Nadal's absence

Rafael Nadal won't be joining his peers Down Under after an MRI revealed that he sustained a tear in his hip muscle at an Aussie Open tuneup event. The Spaniard's latest injury setback means one fewer obstacle for the numerous young guns looking to make a splash at the season's first major. While Nadal has won the "Happy Slam" just twice over his career, he's been a consistent threat in Melbourne, reaching the quarterfinals or better in 14 of his last 16 appearances.

On a bigger scale, Nadal's absence raises more questions about his playing future. The 22-time major champ has already said the 2024 campaign will likely be his last season on the ATP Tour. Another injury just three matches into his comeback bid is further confirmation that the end is near for one of the all-time greats.

Nadal's body is clearly breaking down and can no longer withstand the physically demanding style that's defined his success over the last two decades. The 37-year-old's best option is to get 100% healthy for the clay-court season, as it'll give him an honest shot to compete for another French Open crown. From there, Nadal should have a clearer picture of what lies ahead.

Potential chaos on women's side

The WTA's current top four - Iga Swiatek, Aryna Sabalenka, Elena Rybakina, and Coco Gauff - have separated themselves from the pack over the past 12 months. They won a combined 15 singles titles in 2023 and have hoisted the winner's trophy at six of the past seven majors. With each player in form ahead of the tournament, there's a good chance this year's champion comes from the aforementioned quartet. But chaos is also a possibility.

Swiatek drew former Australian Open winner Sofia Kenin in the opening round and will face 2016 titlist Kerber or 2022 runner-up Danielle Collins if she manages to pass her first test. Jelena Ostapenko and Elina Svitolina also reside in Swiatek's quarter. The pair dealt the World No. 1 her last two major defeats.

Rybakina got thrown into the fire as well. The 24-year-old kicks off her Grand Slam campaign against two-time major finalist Pliskova, who famously beat Serena Williams in the 2019 Australian Open quarterfinals. Rybakina's section of the draw also includes Sloane Stephens, Jessica Pegula, and rising star Qinwen Zheng.

Gauff's attempt to win back-to-back Grand Slams should start relatively smoothly before the difficulty quickly escalates. Leylah Fernandez, who reached the 2021 US Open final, is the highest seed Gauff can face in the third round. A potential showdown against Osaka or Garcia is next should either player navigate their way to the second week. Gauff has a 2-2 head-to-head record against both players.

Shelton looks to build on breakout year

Ben Shelton's first full year on the pro circuit was a roller coaster. The Florida product began the previous campaign with a surprising quarterfinal run at the Australian Open. He then lost 17 of 24 matches at the tour level before catching fire once again at the US Open.

Shelton defeated Dominic Thiem, Tommy Paul, and Frances Tiafoe en route to his maiden major semifinal, electrifying the New York crowd with his big serve, swagger, and soft touch at the net. His momentum continued through to the new year.

Shelton advanced to his first Masters 1000 quarterfinals last October. A week later, he cracked the ATP's top 15 after claiming his first career title in Tokyo. Shelton heads into this year's Australian Open fresh off a semifinal appearance in Auckland.

It's been 21 years since an American man won a Grand Slam singles title. Shelton will have his work cut out for him, especially with a potential US Open rematch against Djokovic on the horizon in the fourth round. But Shelton's got the tools to end that drought and become the United States' next big star.