Andy Ruiz celebrates knocking down Anthony Joshua. (Timothy A. Clary/Agence France-Presse)

In the seventh round of Saturday night’s heavyweight title fight, one of boxing’s biggest stars fell to one knee and then staggered to the corner. Referee Michael Griffin walked to Anthony Joshua, watched him as he made an attempt to recover and then called the fight with 1:26 remaining in the round.

With that, Andy Ruiz Jr. shocked the sport.

Ruiz’s knockout of the heavyweight champion Joshua (22-1, 21 KOs), making his U.S. debut at Madison Square Garden, was predicted by few. Ruiz (33-1, 22 KOs), a 14-1 underdog coming into the night according to the FanDuel sportsbook, scored four knockdowns of the British star, including his TKO victory in the seventh.

Joshua lost his International Boxing Federation, International Boxing Organization, World Boxing Association and World Boxing Organization titles with the upset.

Ruiz, a native of Southern California, is the first fighter of Mexican descent to win a heavyweight title. He was chosen as a late replacement for Jarell Miller in this fight after Miller failed a drug test. The 270-pound Ruiz had little time to prepare, having just fought Alexander Dimitrenko on April 20.

In what was widely expected to be an easy win for Joshua, the sellout crowd of 20,201 at the Garden ended up with an action-packed battle. Both fighters were knocked down in a dramatic third round, with Ruiz going first and then Joshua falling on an overhand right. Ruiz knocked the defending champ down again just before the round ended.

Ruiz knocked down Joshua again in the seventh before his fourth and final fall.

Boxing fans had plenty to say online after the shocking upset. Deontay Wilder, who many believed would one day match up with Joshua, wasted no time in coming after the heavyweight.

Some fans pointed to the “Drake curse” as being responsible for the outcome. The rapper has become something of a bad luck charm for athletes; more than a few surprising results have been preceded by a picture with the Canadian star. It happened to Conor McGregor, Serena Williams and soccer club Manchester City.

And now, despite an Instagram post from March claiming that he was going to buck the trend, Joshua seems to have been hit by the Drake curse as well.

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Bout to break the curse 🦉 #June1st

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Elsewhere, some of boxing’s biggest names marveled at the upset.