Delante 'Tiger' Johnson survived a hellacious scare to advance to the Sweet 16.

The Cleveland-bred welterweight used a final round rally to outpoint Argentina's Brian Arregui in their opening round battle Saturday afternoon at Kokugikan Arena in Tokyo. Johnson won by scores of 29-28 on three scorecards, with the same score landing in favor of Arregui on the remaining two cards.

The opening round saw Johnson boxing on his toes, looking to neutralize the naturally aggressive approach of Arregui who brings his pro style to amateur's highest stage. It doesn't always translate but it served the Argentine boxer well, even if narrowly losing the opening round as Johnson claimed a 10-9 lead on three of the five cards.

Johnson was down twice in round two, one for an official eight count. The 22-year-old welterweight struggled to keep his footing, nearly doing a split as he fell to the canvas in his own corner which was accurately ruled a split.

Arregui lodged an official knockdown mere seconds later, connecting with a left hook to the body and then a clean left hook upstairs as Johnson's chin was in the air. Knockdowns are not scored the same in amateurs as is the case in the pros, though it added to Arregui's dominance to sweep the round. 

Johnson returned to the jab in the third and final round. It worked to a degree, though never to the point of forcing Arregui to take a backward step. Arregui continued to look for openings to crank his straight right and left hook, with Johnson doing a better job of avoiding a big shot finding his chin.

It was enough to advance to the Round of 16. 

The win is the second of the day for the U.S. Olympic boxing team, with Johnson joining Cincinnati's Duke Ragan in the winner's circle. 

Arregui's late placement in Tokyo becomes a short-lived journey. He received an allocation after Venezuela's Gabriel Maestre (3-0, 3KOs) dropped out of competition to continue his pro career.

With his unexpected early exit—and in a fight many will argue he deserved to win—Arregui will likely resume his pro career. 

Johnson—who puts Cleveland boxing in four consecutive Olympics—will next face Ablaikhan Khussupov (Kazakhstan) on Tuesday. 

Jake Donovan is a senior writer for Twitter: @JakeNDaBox