With six successful defenses of The Ring and lineal middleweight titles, Martínez's 50-month reign as champion ranks as one of the longest in the history of that weight class.
[4] A southpaw, Martínez was known as a fast and athletic fighter and his style has been described as "crowd-pleasing",[5] partly because of his tendency to fight with his hands down when out of his opponents' range.
His boxing career suffered a major setback in August 1996 when he broke his left hand, forcing him out of the sport for a year.
[11] Although he considered competing for Argentina at the 2000 Olympics, he decided that he was too old to wait the two and a half years and chose to turn professional in December 1997.
The opponent for his professional debut, Cristian Marcelo Vivas, was disqualified in the second round, giving Martínez his first win.
[13] After his final fight in Argentina, a February 2002 win over Francisco Mora, Martínez decided to relocate to Spain.
It was there that he began his partnership with his current trainer Gabriel Sarmiento, who worked out of a gym in Azuqueca de Henares.
Over the next two and a half years, Martínez won seven fights in a row back in Spain, six of which were against boxers who had losing records.
[13] Soon thereafter, Martínez began to gain recognition and pursue fights in the United States, under the guidance of adviser Sampson Lewkowicz.
Martínez claimed the Interim WBC light middleweight championship on 4 October 2008, beating Alex Bunema via an eighth round retirement.
The fight went the twelve round distance and the scorecards revealed a draw, many ringside observers felt that the decision was a robbery and that Martínez easily outboxed Cintron and should have gained the victory.
[16] On 21 May 2009, WBC light middleweight champion Vernon Forrest was stripped of his title due to a rib injury that would leave him out of action indefinitely.
The sanctioning organizations for boxing recognize that boxers may choose to move up or down in the weight categories, yet they also wish to make all championship belts available to challenge.
Approximately one minute into the second round, Martínez knocked Williams out with an over-the-top left hand to retain his title.
Sergio Martínez's next fight was against undefeated Sergiy Dzindziruk on 12 March 2011 at the Foxwoods Resort Casino, Mashantucket, winning by TKO in 8 rounds.
Martínez then fought undefeated EBU middleweight champion Darren Barker on 1 October at the Boardwalk Hall in Atlantic City.
The first few rounds showed that Barker was actually able to make Martínez uncomfortable in the ring and give him more trouble than expected.
3 Ring Middleweight Matthew Macklin of Ireland on 17 March 2012 at the Madison Square Garden in New York City.
The fight was featured on BBC's boxing schedule for 2011: "18: Madison Square Garden, New York City, Sergio Martinez beat Matthew Macklin by 11th-round KO (The Ring middleweight).
Martinez prepped for this fight against Chavez Jr. in Oxnard, California training under his career long coach, Gabriel Sarmiento.
Despite being fatigued and clearly hurt, Sergio Martínez managed to survive the thrilling 12th round without holding.
After the fight, it was revealed that Martínez had broken his left hand (as early as the 4th round) and torn his right meniscus, the latter of which would require surgery.
[26] After his surgery, Martínez confirmed his next title defense would take place in his native Argentina,[27] in what would be his first fight in his home country since leaving for Spain in 2002.
News agency Reuters reported that Martínez could make his first title defense against British fighter Martin Murray on 27 April 2013 in Argentina.
After a series of setbacks including further surgeries on his knees, Martínez fought again over a year after the Murray fight, losing his WBC, The Ring and lineal middleweight titles to three-division former world champion Miguel Cotto on 7 June 2014, at Madison Square Garden in New York City.
It was evident straight away that Martinez's legs were not there, even with knee braces on and clearly visible, Cotto knocked Martínez down three times in the first round.
"[29] Following the bout, Martínez stated that he wanted to continue his boxing career, and expressed his desire to fight against Manny Pacquiao and Floyd Mayweather Jr.