Conor McGregor surprises before Floyd Mayweather rallies for 50-0

Thank you everyone in Las Vegas and everyone at home who ordered PPV. Thank you @SHOsports and my team @MayweatherPromo. pic.twitter.com/royY4mGHkc

- Floyd Mayweather (@FloydMayweather) August 27, 2017

LAS VEGAS -- Someone forgot to tell Conor McGregor his fight with Floyd Mayweather Jr. was supposed to be a joke.

McGregor, the UFC lightweight champion competing as a professional boxer for the first time in his combat sports career, stunned the crowd at T-Mobile Arena in Las Vegas by taking it to the undefeated superstar before Mayweather rallied and finished McGregor in the 10th round of a fight far more entertaining than anyone had any right to expect.

The stoppage in the 154-pound bout came at the 1:05 mark as Mayweather upped his record to 50-0, surpassing the 49-0 mark set by legendary former heavyweight champion Rocky Marciano.

McGregor announced his presence early by cracking Mayweather with a wicked left uppercut in the first. He attacked Mayweather from awkward angles and used his size advantage to bully Mayweather in the clinch, winning each of the first three rounds in the process.

But the 40-year-old Mayweather, who was competing for the first time since his Sept. 2015 retirement, picked up the pace over the middle rounds. Mayweather started landing often with big right hands, and McGregor noticeably tired as the fight went on.

In the 10th, Mayweather landed one uncontested shot after another until referee Robert Byrd waved the fight off at the 1:05 mark. It was the first TKO loss of McGregor's combat sports career, as he's 21-3 in mixed martial arts, but all three have been by way of submission.

"No one's taking these types of risks. I'll take it on the chin." #ConorMcGregor

Outstanding job, champ. #MayweatherMcGregor pic.twitter.com/mNWELUDikm

- UFC (@ufc) August 27, 2017

In undercard bouts of note, Badou Jack, a Ghanian by way of Stockholm, Sweden, added a world title in a second weight class to his resume. Jack (22-1-3), the former WBC super middleweight kingpin, won the WBA light heavyweight crown with a fifth-round TKO of Nathan Cleverly of Wales. Jack peppered Cleverly with body shots and wicked hooks before the referee waved the bout off at 2:47.

"It's a dream come true," Jack said after his 13th career stoppage. "Can't leave it in the hands of the judges, you gotta go for the kill."

A showcase bout for undefeated Gervonta Davis (19-0) turned out to be something less. Davis was stripped of the IBF junior lightweight title Friday after missing weight by two pounds. Then his fight with Costa Rica's Francisco Fonseca (19-1-1) was marred with a controversial finish.

Davis, who was winning handily on the scorecards, hit Fonseca with a punch to the back of the head, pushed him to the mat, and hit him again while he was down. The referee inexplicably let all this slide and counter Fonseca out at the 39-second mark of the eighth round.

"I guess the camera didn't show the right clip of the camera," Davis said after his 18th career stoppage. "I caught him with a body shot before that punch that hurt him, and he knew that was hurt."