Early in his life Daniel Santos was enrolled in a school specialized in sports, located in a facility designed for the training of Olympic athletes in Puerto Rico.
[2] Two years later he competed in the World Junior Championships that were celebrated in Montreal, Quebec, Canada,[3] where he won the bronze medal, for the second straight time in a competition with worldwide scope.
[5] His next international participation was in the 1995 Pan American games celebrated in Mar del Plata, Argentina, where he won the silver medal.
In his first fight he defeated Ernest Atangana Mboa of Cameroon by RSC (referee stopping contest) at the 2:54 mark of the first round.
Santos debuted as a professional on September 28, 1996, against Andre Hawthorne in Fort Worth, Texas,[7] in a fight where he won by technical knockout in the first round.
Following this fight Santos compiled a record of twenty-one victories, one defeat and one draw before competing for a world championship.
The first draw in Santos' career occurred in a fight with Jose Luis Verdugo, that was part of a card that took place in El Cajon, California.
Jantuah won this contest by technical knockout in the fifth round, marking Santos' first defeat in the professional circuit.
"[12] Sinclair also stated that he expected to win based on his training, he said that all of his sparring partners were southpaws since Santos is one, this preparation also included contracting a new trainer.
At the moment of the fight Margarito was the mandatory challenger appointed by the World Boxing Organization, and it was televised on Showtime Too.
[13] Santos boxed for the vacant WBO light-middleweight title against Yori Boy Campas in a fight that took place at Bally's Event Center in Las Vegas, Nevada.
[17] Early in the fight Santos' strategy consisted of connecting with short punches with his left arm, including a strong impact to Margarito's face in the first round.
On June 28, 2003, he defended against Fulgencio Zúñiga in a card that took place in the Ruben Rodriguez Coliseum in Bayamón, Puerto Rico.
On April 26, 2005, Don King Productions announced that the company had acquired the exclusive rights to promote Santos' fights.
[21] This event took place in a fight card presented in the Madison Square Garden, against José Antonio Rivera.
and that Rivera was a "hardy boxer with strong punches", stating that his physical condition was responsible for his resistance throughout the contest.
[22] On July 11, 2008, Santos competed in his first title fight since returning to action, facing Joachim Alcine for the WBA's light middleweight championship.
[24] In the sixth Santos connected a jab and followed it with a left hook, this combination injured Alcine who was unable to respond to the referee's count, losing the contest by knockout.
[26] Don King proposed a unificatory contest against Sergio Martínez, who held the World Boxing Council's interim championship.
Santos refused the offer, citing that he had less than a month to train for it after a long period of inactivity, but expressed interest in organizing it in another date.
[28] On August 17, 2009, Top Rank won a bid to organize a fight between Santos and the WBA's first contender, Yuri Foreman.
[29] The promotion scheduled the contest to take place as part of the undercard of "Firepower", a card featuring a fight between Miguel Cotto and Manny Pacquiao in the main event.
[31] While taken into custody, Santos was interviewed by a reporter of the popular television gossip show, Lo Se Todo.