Bernard Hopkins is knocked out of the ring, loses retirement bout

Bernard Hopkins wanted to go out with one more memorable moment, but this probably wasn't what he was hoping for.

After eight competitive rounds of boxing in Saturday's main event between the 51-year-old Hopkins and Joe Smith Jr. that was billed as Hopkins' retirement bout, the action came to a chaotic close when Smith unleashed a combo on Hopkins that ejected him through the ropes and out of the ring.

Watch: Bernard Hopkins gets knocked out of ring in final fight

A clearly dazed Hopkins struggled to stand and seemed unaware that the referee was issuing a 20-count for him to return to the ring. With Hopkins unable to beat the count, the fight was ruled a TKO in favor of Smith.

With the win, Smith retained his WBC international light heavyweight title and extended his win streak to 17 straight. However, the prominent narrative going into the bout was Hopkins closing the door on a decorated 28-year pro career.

"The Executioner" took his last walk to the ring draped in a black hood with a remix of Frank Sinatra's "My Way" pouring through the speakers at The Forum in Inglewood, Calif.

Following that dramatic entrance, it took a few rounds for Hopkins to get warmed up as he struggled to deal with the aggressive power punching of Smith. Other than an accidental headbutt that opened up a cut on Smith, there wasn't much offense from Hopkins.

That changed in Round 4 when Hopkins appeared to find his rhythm. He was making Smith miss while connecting with punches of his own, doing enough to outbox Smith even if he wasn't seriously hurting him.

Even with Hopkins catching up in Rounds 5, 6, and 7, Smith was still finding success whenever he cornered Hopkins and his persistence paid off with the shocking sequence in Round 8.

In a backstage post-fight interview, Hopkins said the issue was not with his head but his ankle, adding that it wasn't made clear how much time he had to return to the ring before being counted out. Despite the strange ending, he insisted there's no question this was his last fight.

Hopkins hangs up the gloves after an illustrious pro career in which he ruled over the middleweight division from 1994 to 2005. During that stretch, Hopkins picked up wins over Felix Trinidad and Oscar De La Hoya while collecting and defending the IBF, WBA, WBC, and WBO titles.

His days at middleweight came to an end with a pair of losses to Jermain Taylor in 2005, but Hopkins became a world champion again on May 21, 2011 with a unanimous decision win over Jean Pascal that earned him a light heavyweight belt at the age of 46. That achievement set the record for oldest boxer to win a world title, a record broken by Hopkins himself at age 48 and 49 when he won the IBF and WBA titles, respectively.

Hopkins retires with a career record of 55-8-2.