Sports betting is getting closer to reality at D.C.’s Capital One Arena.

Monumental Sports & Entertainment — which owns the Capital One Arena and D.C.’s Capitals, Wizards and Mystics — is partnering with internationally-known betting and gaming company William Hill U.S. to create the first sportsbook at a professional sports venue in the country.

An exact timetable is not known, but construction of the William Hill Sports Book at Capital One Arena is expected to begin after the deal passes all required regulatory approvals. The D.C. Lottery also has to approve the deal.

Signs at Capital One Arena indicate the sportsbook will open sometime in 2020.

The announcement of the deal Thursday morning was followed by a news conference with Monumental Sports Chairman and Founder Ted Leonsis and William Hill CEO Joe Asher, held at Capital One Arena.

William Hill will operate the facility inside the arena, which will span several floors and be open daily, even on nonevent days at the building.

The sportsbook, which will be located at the southeast corner of the arena where the Green Turtle used to be, will feature full-service food and beverage offerings.

Even though the minimum age to bet in D.C. is 18, the William Hill sportsbook at Capital One will restrict betting to people 21 years old and older.

When the sportsbook launches, people will have the option to wager from the sports bar, or from their seats inside the arena via a William Hill mobile app.

William Hill’s Asher said so-called “in-play betting” helps keep spectators interested.

“So, last night, Caps were down early in the game,” he said during the news conference. “There would have been a lot of people betting on them to come back and win. And, you get good odds when you’re betting on the team that’s behind to come back and win the game. So that just sort of drives further engagement. It gives people reason to watch more, to watch till the very end.”

Betting won’t be limited to games held at the arena.

“We would like to see at lunchtime people from the community coming in and watching soccer matches from around the world,” Leonsis said, citing one example.

He added, “I think it will help our arena come alive.”

For major events that are not staged at Capital One Arena, there is the opportunity to turn the arena bowl into a 20,000-seat TV viewing area.

“What’s this building going to be like on Super Bowl Sunday, or during March Madness, or other prime times on the sporting calendar?” Asher said. “This should be a destination for people to go and spend their time.”

Leonsis said William Hill will manage and be solely responsible for the business of the sportsbook.

“We as sports team owners — we have nothing to do with the odds and the actual gambling and the touching of the money,” Leonsis said.

Since the Supreme Court overturned a federal ban on commercial sports betting, D.C. is one of a number of areas to legalize the practice, bringing it out of the black market.

“It’s not like gambling isn’t happening in an unregulated world,” Leonsis said. “So, our first mission as an industry is to bring what’s illegal into the sunlight. And that’s what having, in Washington, D.C., a major sportsbook will do.”

WTOP’s Jack Moore and John Domen contributed to this report.