Khabib Nurmagomedov retained his lightweight title by forcing Conor McGregor to tap out at the highly anticipated UFC 229 on Saturday night. But he then jumped out of the Octagon and a melee ensued.

Nurmagomedov struck early, locking McGregor up so he couldn't escape and fight back with his signature style. 

The second round was all Nurmagomedov who struck McGregor blow after blow.

In the third round, both appeared fatigued. McGregor was able to stay on his feet most of the round, and both traded punches. 

The two went on to the fourth round, where Nurmagomedov defeated McGregor by submission. 

But following the win, Nurmagomedov jumped out of the Octagon and a team brawl ensued. 

More fireworks ensued and others jumped into the Octagon.

It was McGregor's (21-4) first return to the Octagon in two years—his last bout was a 10th-round defeat to Floyd Mayweather during his pro boxing debut a year ago at the same arena. Mayweather won by TKO. Irishman McGregor, the former two-division title holder, beat Eddie Alvarez in his last UFC fight in November 2016.

The undefeated Russian Nurmagomedov (27–0) last beat Al Iaquinta by decision for McGregor’s former lightweight title on April 7 at UFC 223.

The highly anticipated matchup came after the 30-year-old McGregor was arrested for disorderly conduct after throwing several objects at Nurmagomedov's bus at UFC 223, injuring two fighters. He struck a plea deal last month over his role in the incident.

At the two's weigh-in Friday, McGregor slappedNurmagomedov's fist and then tried kicking him.

According to The Associated Press, McGregor is getting a guaranteed $3 million purse along with untold millions in a cut of pay-per-view sales, while Nurmagomedov is guaranteed a healthy $2 million.