McGregor kicked off 2020 in grand style, knocking out Donald Cerrone 40 seconds at UFC last January. He aimed to compete three times last year, culminating with a championship bout with rival and lightweight champion Khabib Nurmagomedov. 

However, a litany of factors caused combat sports' biggest star to remain on the shelf for the remainder of the calendar year. 

Once again, McGregor returns in the first month of the year, as he takes on Dustin Poirier in the main event of UFC 257 on Saturday from Etihad Arena in Yas Island, Abu Dhabi. 

It was a long, winding road to get to the lightweight rematch between former world champions.

DAZN News breaks down how we got to UFC 257: Poirier vs. McGregor 2.

Retirement

McGregor grew frustrated with UFC management, particularly president Dana White, for refusing to book him in a fight. We were three months into the COVID-19 pandemic, which shut the UFC down for nearly two months. McGregor wanted to compete so people could take their minds away from not doing everyday activities. Understandably, the UFC didn't see it that way as McGregor events are enormous revenue generators at the gate. The company wanted to maximize revenue at an uncertain time in the world. 

Upset at the matter and with no fight on the horizon, McGregor announced after June's UFC 250 that he would be retiring for the second time. 

Private messages released

McGregor was three months into retirement with no sign of him signaling a return. Behind the scenes, though, showed a different story.

McGregor had grown more agitated at White because a fight agreement couldn't be reached. Near the end of September, McGregor took to Twitter and revealed private conversations he had with White that occurred a short time after his KO of Donald Cerrone.

Initially, McGregor had two fights in mind, with UFC veteran Diego Sanchez in his native Ireland being the icing on the cake. White scoffed at the idea of Sanchez. McGregor countered with current interim lightweight champion Justin Gaethje, but the Irishman didn't want to wait that long to return to action.

Reports surfaced earlier last year of McGregor being a replacement fighter if either lightweight champion Khabib Nurmagomedov or Tony Ferguson, scheduled for UFC 249 on April 18, dropped out. COVID-19 shut the door on the highly anticipated fight as Nurmagomedov had gone back to Russia to be with his family.

But McGregor ended the thought of being a fill-in and had wanted to set his own schedule and even proposed a massive card in Los Angeles. 

When the messages came, White was extremely upset at McGregor's actions and said that was the lowest thing you could ever do between a fighter and a promoter. 

McGregor proposes charity MMA match with Poirier 

Things were not looking good at a reconcilation with White, so McGregor decided he could do an event independently. A couple of days after he leaked the messages, McGregor took to Twitter again and proposed a fight to Poirier. Some of the proceeds would go to Poirier's charity, The Good Fight Foundation, and some to charities that McGregor is involved with in his native Ireland and the United States. On top of that, the former two-division world champion said he'd donate $500,000 to Poirier's charity. 

Poirier responded that he would be down for the idea and talks started between the two. 

White delivers an ultimatium to McGregor 

Seeing the considerable interest in a possible McGregor-Poirier charity bout, White immediately thought of booking the two under the UFC banner. Poirier was down for that idea as well, but McGregor was balking. He wanted to get another fight in before the year closed and suggested UFC 256 on Dec. 12. White didn't budge. He gave a take-it-or-leave-it offer to his biggest star for Jan. 23.

"We offered him a fight. We got him his own date," White told ESPN.

"We didn't have a date this year. We have everything laid out for this year, with world champions fighting for titles. He wants to fight Dustin Poirier, apparently, so we went to [broadcast partner] ESPN and got him his date.

"He's been offered Dustin Poirier on Jan. 23. It's a yes or no answer."

Poirier vs. McGregor 2 is agreed upon for UFC 257

It took a little more than a month after White's final offer, but terms were agreed upon for Poirier to battle McGregor at UFC 257 on Saturday, Jan. 23. To Poirier, it was the social media interaction with McGregor to kick start everything because he didn't feel the rematch was on anybody's radar.

"I didn't think this fight was gonna be my next fight," Poirier admitted to DAZN News. "I didn't know if Conor was retired or coming back or fighting again at 170. He hasn't been that active. When he did come back, he was fighting at welterweight. I didn't really see this as a possible matchup, but social media is what started this. We all get consumed into that stuff. If it wasn't for Conor and I interacting on social media, then this fight doesn't happen."