Rafael Espinoza has pulled off a massive upset…

The 29-year-old Mexican boxer, an unheralded featherweight contender, shocked the boxing world on Saturday, after upsetting two-time Olympic gold medalist Robeisy Ramirez to claim the WBO championship.

Espinoza (22-0, 18 KOs) entered the bout with a pristine professional record, although the majority of his work had come against relatively unknown competition in Mexico.

Ramirez (13-2, 8 KOs) was a 15-1 betting favorite, and the bout took place in front of a very pro-Ramirez crowd at Dodge City Center near Miami. It was seen as Ramirez’s fight to lose.

Espinoza clearly didn’t see it that way. The lanky featherweight, in his first world title appearance, threw nearly 1,000 punches over the course of 12 rounds and won a majority decision via scores of 115-111, 114-112 and 113-113.

The 12-round affair immediately qualified as a fight of the year candidate. Espinoza went down from a right hook to the chin in the fifth, while Ramirez took his turn on the canvas from a barrage of punches in the 12th.

Despite not having fought past a third round in three years, Espinoza looked as if he could have fought another 12 at the conclusion. Volume was his greatest weapon, and he out-landed Ramirez 103 to 33 in the final three rounds.

The fight played out in three chapters. Espinoza’s length and volume frustrated Ramirez early, and Espinoza jumped out to a four-round lead on most scorecards. Everything turned in the final second of the fifth, when Ramirez dropped Espinoza with a short right hand. Espinoza barely survived the count and was saved by the bell as soon as action resumed.

Ramirez, 29, of Cuba, hurt Espinoza several more times in the middle frames. Espinoza’s right leg also appeared compromised at one point, after an awkward lower body clash between the two competitors. By the eighth round, it looked like normalcy had returned to the ring and Ramirez was in control, but Espinoza then somehow hit another gear.

The gutsy fighter from Guadalajara threw 995 punches to Ramirez’s 376, according to Compubox. Ramirez was far more consistent, as Espinoza only landed 222 to Ramirez’s 119. But there was no question the volume had taken its toll on the defending champion by the 12th round, and Ramirez was running on fumes. Espinoza threw 120 punches in the 12th round alone.