It’s official — CNN has announced which Democratic presidential candidates will share the stage in this month’s second, two-night Democratic presidential debate. After a somewhat absurd live event involving three random drawings, the outcome is:

Night 1 (Tuesday, July 30): Vermont Sen. Bernie Sanders, Massachusetts Sen. Elizabeth Warren, South Bend Mayor Pete Buttigieg, former Texas Rep. Beto O’Rourke, Minnesota Sen. Amy Klobuchar, author Marianne Williamson, former Maryland Rep. John Delaney, former Colorado Gov. John Hickenlooper, Ohio Rep. Tim Ryan, and Montana Gov. Steve Bullock.

Night 2 (Wednesday, July 31): Former Vice President Joe Biden, California Sen. Kamala Harris, New Jersey Sen. Cory Booker, former HUD Secretary Julián Castro, businessman Andrew Yang, Washington Gov. Jay Inslee, Hawaii Rep. Tulsi Gabbard, New York Sen. Kirsten Gillibrand, New York City Mayor Bill de Blasio, and Colorado Sen. Michael Bennet.

The drawing wasn’t entirely a random one — beforehand, CNN split the candidates into three groups depending on how they were polling, and ensured each group would be split evenly among the two debate nights. Then, there was a drawing from each group.

That is: each debate night was guaranteed to feature two of the four top-polling candidates, three of the six middle-tier candidates, and five of the ten bottom-tier candidates. This methodology was designed to avoid a situation where, in a purely random drawing, too many of the top candidates would be placed together.

Biden and Harris will square off again

The most interesting question was how the four top-polling candidates — former vice president Joe Biden, Sen. Kamala Harris, Sen. Bernie Sanders, and Sen. Elizabeth Warren — would be paired off.

It’s important — for the first debate, if Harris wasn’t put onstage with Biden, she wouldn’t have had the chance to challenge him face-to-face on his opposition to busing — which proved to be one of the most consequential moments of the campaign so far.

The pairing of Biden with Harris for the second debate — on night two — guarantees a sequel to that tense confrontation.

Harris challenged Biden’s record on civil rights, elevating questions about how the former vice president will defend his decades-long record, and whether he’s in touch with today’s Democratic electorate. The exchange almost immediately doubled Harris’s support in polls, cementing her place among the top tier contenders, and seemingly revealing Biden’s weakness as a frontrunner.

Now, though, Biden will get a do-over. And that’s an important opportunity for him. He will have had ample time to prepare this time around, and could make a more spirited defense of his record, or challenge Harris’s caginess on whether or how she would really bring back busing. (And it would be difficult for Biden to handle the topic more poorly than he did last time.) But Harris is a formidable opponent who has damaged Biden already and will have the opportunity do more.

Sanders will be pitted against Warren

The matchup of Sanders and Warren on night one is also intriguing. They’re the two major candidates who have eschewed big dollar fundraising and who want to push the party much further to the left on economic issues.

But their teams argue that despite these broad similarities, Sanders and Warren are actually quite different in their approach to politics. Sanders seems more committed to making Medicare-for-All a top priority, and argues he can overcome entrenched interests by fomenting a people-powered “political revolution.”

Warren, meanwhile, is more inclined toward policy wonkery and an inside game of making change through the executive branch and regulatory policy. (Both candidates have generally focused more on domestic issues than foreign affairs, though since the 2016 campaign Sanders has made some interesting foreign policy moves.)

It’s Warren’s campaign that has been on the rise of late, as she’s effectively branded herself as the candidate with a substantive plan for (almost) everything. Sanders, meanwhile, has slipped a bit, from the clear second place behind Biden to something more like a three-way tie for second with Warren and Harris.

So now, Sanders has an opportunity to try and take Warren down a peg, and argue that he’s the candidate the party’s left flank should truly support. It’s unclear whether going on the offensive would be the best move at this point, though — the two could also decide to stress their areas of agreement, in contrast to the other top contenders.