The 11th Democratic debate is set for Sunday night, and the first one-on-one face off between Joe Biden and Bernie Sanders will look much different than was originally planned.

Here’s everything you need to know about the debate:

The two-hour debate is scheduled for 8 p.m. ET, in a different location than originally planned. It had been scheduled to take place in Phoenix — Arizona is one of four states that have a primary on Tuesday — but the venue was switched to Washington, D.C., after organizers decided to do away with the audience because of coronavirus concerns. The debate will be held at the studios of CNN, which is hosting the event with Univision.

The location and lack of an audience aren’t the only coronavirus-driven changes. One of the scheduled moderators, Univision anchor Jorge Ramos, had to bow out because he’d been in proximity of somebody who’d been in direct contact with a person who tested positive for the virus. Ramos is symptom free, but staying away out of “an abundance of caution,” organizers said. Univision’s news anchor, Ilia Calderón, will moderate in his place.

The other moderators are CNN’s Jake Tapper and Dana Bash.

While there were seven candidates on stage at the last Democratic debate in South Carolina not even three weeks ago, five of them — Mike Bloomberg, Pete Buttigieg, Amy Klobuchar, Tom Steyer and Elizabeth Warren — have since dropped out.

That left only Biden, Sanders and Hawaii Rep. Tulsi Gabbard still in the race. The Democratic National Committee said that to qualify for the stage, candidates need at least 20 percent of the delegates that have been allocated to date. That means no Gabbard, who’s only claimed two delegates in her quest for the Democratic presidential nomination. As of Sunday, Biden had 860 and Sanders 706, according to NBC News’ delegate counter.

The rules for the debate have not yet been announced, but Sanders said in a speech this past week that he has several questions he’d like to ask Biden, including about healthcare costs, immigration and climate change. “Joe, what are you going to do?” Sanders said in his address, which came after what the Vermont senator acknowledged had been a “tough night” for him at the ballot box, including losing to Biden in Michigan and a slew of other states.

With Sanders on the ropes, the debate comes before voting on Tuesday in Florida, Ohio, Illinois and Arizona. If Sanders doesn’t do well and close the delegate gap with Biden, the end of his campaign could be approaching.

The debate will air live on CNN, CNN en Español, CNN International and Univision and stream live on CNN.com’s homepage.

NBCNews.com will cover the debate with a live-blog, stories and analysis.