In the main event for the vacant UFC light heavyweight championship, Anthony Johnson squares off against Daniel Cormier. The co-main event features another title bout with Chris Weidman defending the middleweight title against former light heavyweight champion Vitor Belfort.

MORE: UFC 187 odds, picks | Rumble, Cormier fighting for respect | Better late than never for Weidman, Belfort

In other action, No. 3 ranked lightweight Donald Cerrone faces late replacement John Makdessi. Then in a battle of top heavyweights, No. 3 ranked Travis Browne goes against former heavyweight champion and No. 8 ranked Andrei Arlovski. 

Coverage begins on UFC Fight Pass at 6:30 p.m. ET, switches over to Fox Sports 1 at 8 ET and then the main card starts on PPV at 10 ET. 

There are plenty of reasons to watch tonight’s UFC 187. We have narrowed it down to five.

New king at light heavyweight: It’s been over four years since anyone not named Jon Jones held the light heavyweight title. Jones defeated Mauricio “Shogun” Rua by third round stoppage at UFC 128 in March 2011 to win the title. Since then, Jones had reigned supreme making eight consecutive title defenses.

It all came crashing down in April when Jones was stripped of the belt and suspended indefinitely by UFC president Dana White when he was allegedly involved in a hit-and-run accident involving a pregnant woman in New Mexico. Jones was scheduled to face Johnson tonight and White replaced him with Cormier. 

Cormier’s last fight was for the title in a loss to Jones at UFC 182 in January. Johnson also fought in January at UFC on Fox 14 beating Alexander Gustafsson by first round stoppage.

This fight can go a variety of ways as both guys are strong on the feet. You would think Cormier would have the advantage on the ground as he is a two-time Olympic wrestler. Johnson is no slouch on the ground though. He went to Lassen College in California on a wrestling scholarship. He has never been taken down to the mat since he moved down to 205 pounds in 2012. 

We should be in for a terrific main event and crown a new king at 205 pounds.

Co-main event grudge match: This is a fight 18 months in the making. Through various injuries and TRT bans, Weidman and Belfort will finally happen. In the lead-up, tension was there between the two but were respectful to each other until Friday’s weigh-in. 

During the staredown, Weidman started jawing at Belfort and accusing him of still being a cheater. ESPN reported earlier this week that on March 16 Belfort was administered a random drug test. His urine test produced a testosterone level of 1,200 ng/dL. On April 28, his level was 500 ng/dL. Most labs consider a range of 348 to 1,197 ng/dL to be normal. Those are acceptable numbers by Nevada State Athletic Commission and the fight will happen this evening.

Is Belfort cheating? Who knows, but Friday’s incident added drama to the fight. 

Next lightweight title challenger: Cerrone has won seven consecutive fights heading into Saturday’s tussle fight with Makdessi. With a win, Cerrone will be next in line to face lightweight champion Rafael Dos Anjos. In the past, Cerrone has been one fight away from getting a crack at the belt and come up short. 

Makdessi is playing with house money. He is replacing Khabib Nurmagomedov who suffered an injury in training for the fight. He fought at last month’s UFC 186 beating Shane Campbell. This will be the biggest test of Makdessi’s career. If he loses, it’s no big deal. He was supposed too. 

If he wins, he vaults up to top contender status at 155 pounds. Anything can happen in MMA. 

Former roommates battling for heavyweight title shot: Arlovski and Browne were not only training partners at Jackson-Winkeljohn MMA but also roommates. Arlovski lived in Browne’s apartment and moved out when the fight was booked. 

The winner of this fight has a great chance to face the winner of the heavyweight title unification bout between Cain Velasquez and Fabricio Werdum at UFC 188 in June. After losing to Werdum in April 2014, he bounced back to beat Brendan Schaub at UFC 181 in December. Arlovski returned to the UFC in September defeating Antonio Silva at UFC Fight Night 51. Whoever lands the first big shot is the one who will most likely win the fight.

Flyweight tournament:  UFC flyweight champion Demetrious Johnson doesn’t have an opponent for his next fight. A good chance it happens tonight as John Dodson battles Zach Makovsky in the preliminary card headliner and Joseph Benavidez faces John Moraga to kickoff the main card. 

Benavidez, Dodson and Moraga have faced Johnson in the past. They were unsuccessful in taking the title from him. The closest one to beating the champion was Dodson, losing a close decision at UFC on Fox 6 in Jan. 2013.

Anyone of these four would be a viable challenger to Johnson. It is going to come down to who looks the most impressive.

Here is the complete UFC 187 card. 

MAIN CARD (Pay-Per-View, 10 p.m. ET) - Daniel Cormier vs. Anthony Johnson for vacant light heavyweight title - Chris Weidman vs. Vitor Belfort for middleweight title - Donald Cerrone vs. John Makdessi - Andrei Arlovski vs. Travis Browne - Joseph Benavidez vs. John Moraga

PRELIMINARY CARD (FOX Sports 1, 8 p.m. ET) - John Dodson vs. Zach Makovsky - Josh Burkman vs. Dong Hyun Kim - Uriah Hall vs. Rafael Natal - Nina Ansaroff vs. Rose Namajunas

PRELIMINARY CARD (UFC Fight Pass, 6:30 p.m. ET) - Colby Covington vs. Mike Pyle - Leo Kuntz vs. Islam Makhachev - Josh Sampo vs. Justin Scoggins  

Steven Muehlhausen is a boxing and MMA writer and contributor for Sporting News. Email him at [email protected] and can find him on Twitter @SMuehlhausenMMA.