Bulgarian Grigor Dimitrov, ranked in the top 10 (9th) for the first time in his career, had his best Grand Slam showing at Wimbledon, when he lost to eventual champion Novak Djokovic in a bruising four sets. (Pavel Golovkin/Associated Press)

As an 18-year-old Grigor Dimitrov used to be called “Baby Fed” for a style of play similar to Roger Federer’s. Then he became known for being Maria Sharapova’s other half. Now the 23-year-old has made a name for himself, falling to Wimbledon champion Novak Djokovic in four bruising sets in the semifinals at the All England club earlier this month.

Ranked in the top 10 (No. 9) for the first time in his young career, Dimitrov is not far from a first Grand Slam title, and he knows it.

“I think I’m pretty close,” Dimitrov said. “I think I just need to believe that I can actually go through those matches and come with that confidence.”

Dimitrov, No. 7 Milos Raonic and No. 11 Kei Nishikori are players the ATP Tour has promoted as the next generation of stars who will eventually take the throne from reigning tennis royalty Federer, Djokovic and Rafael Nadal.

Dimitrov, Raonic and Nishikori — all younger than 25 — will highlight a strong men’s singles field in the Citi Open, which begins Monday at the William H.G. FitzGerald Tennis Center in Rock Creek Park.

“I’ve been doing the tournament for 47 years, and the depth of this year’s field is something we just never had,” said Donald Dell, the tournament’s founder. “I can honestly say this is the best quality of field I’ve been a part of.”

Fifth-ranked Tomas Berdych will be the top seed in the men’s singles field, giving the Citi Open three top 10 players for the first time since 2010. The tournament boasts eight players in the top 25, even with Friday’s withdrawal of 23rd-ranked Gael Monfils.

Top American and 2013 Citi Open runner-up John Isner said the stronger field makes the Citi Open one of the toughest ATP World Tour 500-level events. The Citi Open can be a tuneup for not only the U.S. Open, but also for the rest of the U.S. Open series with stops in Cincinnati and Canada ahead. Tournament Director Jeff Newman said it becomes a must-play week for players looking to secure significant ranking points heading into those tournaments.

“I think it’s more exciting,” Isner said. “I want to go up against guys that are ranked higher than me because that’s normally a good thing. That means I’m progressing well within that tournament. But it’s good for the tournament. It’s good for everyone. It’s going to be a high level of competition.”

Dimitrov might be the most intriguing player in the men’s field, even though he won’t be the top seed. Djokovic needed to win six of the final seven points in a fourth-set tiebreaker to oust him at Wimbledon.

Legendary tennis coach Nick Bollettieri said that of all men’s tennis players, Dimitrov is who he most wants to coach because of his “all-around game.” Dimitrov has four career singles titles, three this year.

“These are the players that are coming,” Bollettieri said of the Citi Open field. “That’s what’s beautiful. These are the players that are going to be around in the next five to 10 years.”

Dimitrov stands out with a one-handed backhand that’s a rarity among younger players. He said it wasn’t something he specifically chose to do, but something he just picked up while training under his father and coach when he was younger. Federer also has a one-handed backhand, hence Dimitrov’s “Baby Fed” tag.

“You don’t see many people doing it with one hand anymore,” Dimitrov said. “That’s an advantage. It’s kind of nice to just be different.”

He grew up in an athletic family, his dad his tennis coach and his mom a former volleyball player. When the praise and the Federer comparisons started, the Bulgarian — already the best tennis player to come out of his country — took it in stride and leaned on his parents for support. “It’s a good kind of pressure” because it’s positive, he said.

Being a Wimbledon semifinalist and breaking into the top 10 wasn’t a surprise to Dimitrov, who believes those things follow hard work and consistently playing well. That’s why he knows there’s more to come.

“I think I’m getting into that space where I’m consistently playing against the top players, and I’ve beaten them,” Dimitrov said. “That shows and proves that I’m ready to do that. Now it’s really important to stay on the right track and play the best tennis that I can.”