Floyd Mayweather lived up to a vow against Conor McGregor that few thought he would keep

Weeks before his fight against Conor McGregor, Floyd Mayweather told ESPN's Stephen A. Smith that he would "go after" McGregor.

Mayweather said he owed it to fans who were disappointed with his 2015 blockbuster bout against Manny Pacquiao in which he fought a tactical, defensive fight and won by unanimous decision.

Many fans and analysts were skeptical of the promise, as Mayweather has historically been a defensive fighter.

Likewise, many boxing analysts believed McGregor's best chance at beating Mayweather would be to land some haymakers if he got an opening. Mayweather fighting an offensive fight would perhaps give McGregor that chance.

However, after a surprisingly entertaining 10-round bout, it's safe to say that Mayweather kept his vow. After three quiet early rounds in which McGregor held his own and perhaps even won, Mayweather became aggressive. Perhaps sensing fatigue in McGregor, Mayweather suddenly began going toward McGregor, throwing big right hands at McGregor's head.

As ESPN Stats and Info noted, it was a tale of two fights, as Mayweather picked up the slack as the fight went on.

Some theorized that Mayweather's slow start was his way of gauging McGregor while others theorized that Mayweather just wanted to give fans a show. Mayweather admitted after the fight that he and his team decided to let McGregor come out aggressively, then after a few rounds, go after him. It seemed to work.

However, this wasn't just Mayweather taking quick jabs as McGregor tired out - Mayweather was in a rarely seen offensive mode, actively pursuing McGregor and throwing big shots.

After the fight, Mayweather again mentioned the Pacquiao fight, saying: "I think we gave the fans what they wanted to see. I owed them for the Pacquiao fight. I had to come straight ahead and give the fans a show. That's what I gave them."

After looking like the usual Mayweather in the first three rounds, he came to life later on and showed an unusual side in the ring. He finished his career not only with a 50-0 record, but with a fight that was impressive, even if it came against a nontraditional opponent.