AGE: 23 | BIRTHPLACE: Bratislava, Slovak Republic | ALREADY: Claimed the title of 2012 ATP Newcomer of the Year.
Only one man won his first-ever ATP tournament title in 2012: the big lefthander known as Klizko. After winning four titles on the second-tier Challenger Tour in 2012, he captured the St. Petersburg Open crown in September to cap off a year in which he rose from No. 117 to No. 29. He also made his deepest run in a grand slam tournament, reaching the fourth round of the U.S. Open. Along the way, he notched his first victory against a top 10-seeded player when caught Jo-Wilfried Tsonga off guard in the second round by covering the baseline with big forehand shots. Many reports attributed that win to an off day by the No. 6-ranked Tsonga, but Klizan deserved more credit. The 6-foot-3 clay-court specialist serves with both power and placement, giving him the ability to disrupt opponents' rhythm -- and helping them make as many mistakes as possible. If he can develop a bit more consistency, Tsonga won't be the last high seed making match-deciding errors against Klizko. -- Carmen R. ThompsonKei Nishikori
When Kei Nishikori turned pro in 2007, his coaches dubbed him Project 45 to remind him of his goal: Earn a ranking higher than 46, thus becoming the most successful male tennis player in Japanese history. He checked that accomplishment off the list in October 2011, but his rise didn't stop there. After reaching the quarterfinals in both the 2012 Australian Open and the Olympics, he defeated Milos Raonic in the final of October's Tokyo Open to win his second ATP title and rise to No. 15 in the world. Now he -- and tennis observers everywhere -- are thinking Project 10. At 5-foot-10 and 150 pounds, there's concern that he's undersize and underpowered compared with the top men on tour. But he's won against several of them -- including Novak Djokovic, Tomas Berdych and Jo-Wilfried Tsonga -- with a combination of scrappy, speedy defense and crafty shot making. "He's a great player, he has great movement and he's a shot maker," Nick Bollettieri, who runs the famed Florida tennis academy where Nishikori trains, told The Tennis Space. The biggest potential Project 10 killer? A nagging right ankle injury. -- Carmen R. ThompsonMilos Raonic
With a comet-tailed serve that should require military clearance, Milos Raonic has zoomed from No. 150 to No. 13 in just two years. Just as worrisome to the dozen guys above him, Raonic leads the tour in three key categories: first serve points won, service games sealed and break points saved. "I try to keep my opponents off balance," he says. That was evident in the twin defeats he handed Andy Murray, on clay in Barcelona in April and under a blazing Tokyo sun in October. Both times Raonic used booming first and second serves to draw Murray into defensive knots. At the bigger stage of the U.S. Open, however, he couldn't stop the Murray Express in the fourth round. At 6-foot-5, Raonic stands comfortably eye to eye with towering baseliners Tomas Berdych and Juan Martin del Potro. He'll need better anticipation and attack-style conditioning to move past them in the top 10. But his 149 mph serve is already raising the bar on a punishing men's game we didn't think could get any more physical. -- Shaun AssaelLaura Robson
For long-suffering British tennis fans, the U.S. Open brought more than one ray of light: As Andy Murray cruised to his first grand slam title, his Olympics doubles partner showed signs of becoming Great Britain's breakout star on the women's side. Robson ushered Kim Clijsters into retirement in the second round and shut down world No. 8 Li Na in the third, then fought off eight match points against reigning champion Samantha Stosur before falling in straight sets. The three matches offered harbingers of why Robson, ranked No. 53, could become the first British woman to hoist a slam trophy since Virginia Wade in 1977. Against Na's stellar footwork, the 5-foot-11 Robson showed off her improved mobility, keeping points going until she could seize the advantage. Her smoking forehand kept Stosur on the run for a bit. "There aren't many teenagers in the top 100 now, and she's right up there with the best in the world for her age," Murray told Britain's Daily Record. She needs to work on her lateral speed, but Great Britain may not have to wait much longer for its next grand slam champion. -- Carmen R. Thompsonhttp://espn.go.com/espn/next2012/sto...ine-next-issueSloane Stephens
Even without her one-two punch of a 115 mph serve and a forehand that can change altitude more often than a plane in a storm, Sloane Stephens would be the talk of the women's tennis tour. That's because she's smart, bubbly and full of the one thing that's been lacking lately -- fun. While veterans offer up stony sound bites, the 19-year-old strings together answers with commas to separate all of the "fer sures," "you knows," and "like wow guys." Her string of slam appearances, though, is what's really turning heads. Stephens went into the French Open ranked 71st and tore through the first three rounds without dropping a set. In the third round of the U.S. Open, she was a set ahead of Ana Ivanovic, a former No. 1, before losing her momentum and the match. Sloane's late father, former NFL running back John Stephens, gave her the upper body power that lets her bang with the best at the baseline. And her mom, Sybil, an all-American swimmer in college, gave her the legs that belong in a Mickey Spillane novel. -- Shaun Assael