Argentinian boxer Sabrina Perez is mourning the loss of her husband and trainer, Diego Arrua, who suffered a heart attack during Perez’s title fight Friday night.

Arrua was in Perez’s corner for the interim WBC featherweight title bout in Mexico with Australian Skye Nicolson.

The 58-year-old Arrua collapsed between the ninth and 10th rounds.

Perez, 36, who lost the bout via unanimous decision, wasn’t in the ring when the results were announced following the fight, according to multiple reports.

WBC president Mauricio Sulaiman confirmed Arrua’s death later in the evening.

‘It is with deep sadness that we have been informed of the sudden death of Argentine coach Diego Arua, who suffered a devastating heart attack during the Sabrina Pérez fight in Tijuana,” wrote Sulaiman, per the Daily Mail. “The medical services did everything possible and he died at the QDEP general hospital.”

Condolences poured for Perez, with Nicholson among those paying their respects online Saturday.

“Today I’m leaving Tijuana with a heavy heart. All of my thoughts and prayers are with Sabrina Pérez and her family during this incredibly painful and horrible time,” Nicholson wrote. “My heart is broken for this warrior and I can’t even imagine what she is going through.

“Please hold your loved ones close, life is not fair and you never know when will be your last moment with someone. May Diego Arua rest peacefully.”

Friday’s title fight was promoted by Matchroom Boxing, which posted a message after the bout, according to ESPN: “Our thoughts and condolences are with Sabrina Perez and your loved ones.”