Alistair Overeem defeats Junior dos Santos by TKO

— -- ORLANDO, Fla. -- A UFC heavyweight fight between Junior dos Santos and Alistair Overeem didn't deliver the action some expected -- but it did deliver the knockout.

Overeem (39-15) scored the 17th knockout of his 16-year MMA career on Saturday, as he knocked dos Santos (17-4) down with a looping left hand in Round 2 and finished him with strikes on the ground. The heavyweight fight co-headlined UFC on Fox inside Amway Center.

The bout was originally supposed to take place for the UFC title in May 2012, when dos Santos was the defending champion. The month before the fight, however, Overeem failed a random drug test in Nevada and was not licensed to fight. The two have always seemed to be on a collision course since, but the matchup never came together until this weekend.

Fans were quick to boo a lack of action in the first round, as the two heavies showed a lot of mutual respect. Overeem slowly picked away at dos Santos with leg and body kicks though, which eventually led to the left hand.

"Junior is a very, very dangerous opponent," Overeem said. "You have to fight cautious against him. He throws bombs. We had to soften him up a little bit. He's very dangerous, very strong. He has fast hands. Today it came together."

Dos Santos, who trained for the fight with a new camp at American Top Team in Coconut Creek, Florida, protested the stoppage by referee Dan Miragliotta. The 31-year-old Brazilian was in the action of getting to his feet as the fight was stopped, but Overeem was positioned behind him, throwing hard shots to his undefended head. The loss was the second by knockout of dos Santos' career.

According to Fightmetric, Overeem outlanded Dos Santos in total strikes 19 to 17, despite throwing 17 fewer. The majority of his offense prior to the left hand came in the form of kicks, but he also bloodied dos Santos' nose in the first round with punches. In the second round, he opened a cut over dos Santos' right eye with a left cross.

A former Strikeforce and DREAM heavyweight champion, Overeem signed with the UFC in 2011 and knocked out former champion Brock Lesnar in his UFC debut. He hit a skid afterward, losing three of his next four fights but has since rebounded with three consecutive victories.

Fighting out of Holland, and also with an association to Jackson-Winkeljohn MMA in Albuquerque, Overeem entered Saturday's bout ranked No. 7 in the division by ESPN.com. According to reports, it was the final fight on Overeem's UFC contract. Should he re-sign with the UFC, he'd be in a good position to finally fight for the promotion's title. Champion Fabricio Werdum is scheduled to defend the belt against Cain Velasquez on Feb. 6.

"I feel very confident with the team around me, from Holland and Albuquerque," Overeem said. "I feel very confident for that next title shot."

Diaz outpoints Johnson in slugfest

In one of the best lightweight fights of the year, Nate Diaz (18-10) defeated Michael Johnson (16-10) via unanimous decision (29-28, 29-28, 29-28) in a back-and-forth slugfest that saw a combined 246 total strikes landed. Diaz, who made his first appearance in 12 months, used his reach advantage well, tagging Johnson with straight left hands one after another. Johnson responded with hard leg kicks in each round and several combinations in close, punctuated by his own left hand. The fight featured just one attempted takedown, by Johnson at the very end of the final round.

As he's known to do, Diaz, the younger brother of UFC welterweight Nick, taunted Johnson throughout the 155-pound contest. He pointed and laughed at Johnson any time a big left hand landed. He slapped him with an open hand and then showed Johnson his palm. Johnson hurt Diaz with a right hand late in the fight and left the Octagon disgusted after the result was read. In his post-fight speech, Diaz called for a fight against newly crowned featherweight champion Conor McGregor.

"Conor McGregor, you're taking everything I worked for," Diaz said. "I'm fighting you next."

Kowalkiewicz shines in UFC debut

Polish strawweight Karolina Kowalkiewicz (8-0) scored a major win in her UFC debut, knocking off ranked contender Randa Markos (5-3) in a unanimous decision (30-27, 29-28, 29-28). Kowalkiewicz survived a bad position in the second round, when Markos managed to take her back and threaten with a choke. She was far more effective than Markos on the feet, however, and scored some heavy ground and pound in the third.

Oliveira submits Jury in Round 1

Featherweight Charles Oliveira (21-5) collected his eighth submission win in the UFC, tapping Myles Jury (15-2) with a guillotine at 3:05 of the first round. The Brazilian turned in a nearly flawless performance, taking Jury down early on and transitioning to his back. After Jury managed to escape that position and get back to his feet, Oliveira wrapped up the neck during the scramble and pulled guard for the win. Oliveira missed weight by four pounds prior to the win and forfeited 20 percent of his purse.

Marquardt finishes off Dollaway

Middleweight Nate Marquardt (33-16), of Denver, scored a highlight-reel knockout over CB Dollaway (15-8) at 0:28 of the second round. The outcome of the fight changed on a dime, as Dollaway had hurt Marquardt with punches moments before the knockout punch. As Dollaway charged in for a finish, Marquardt planted a sturdy counter right to the chin and that was all she wrote. It is the 10th knockout of Marquardt's career.