ARLINGTON, Texas – Frank Sanchez’s fight Saturday night ended earlier than his previous bout, but in unfulfilling fashion.

Nagy Aguilera determined he couldn’t continue in the sixth round of their scheduled 10-round heavyweight bout because Sanchez landed a right hand behind his head. Aguilera was given plenty of time to recover from Sanchez’s inadvertent foul, but they went to the scorecards once Aguilera declined to move forward with the remainder of their bout at 1:42 of the sixth round on the Canelo Alvarez-Billy Joe Saunders undercard at AT&T Stadium.

Judges Javier Alvarez, Tim Cheatham and Glenn Feldman all scored each of the six rounds for Sanchez, 60-54. Referee Ruben Perez determined Sanchez’s foul was accidental, which was why they went to the scorecards.

The 28-year-old Cuban contender improved to 18-0 (13 KOs). The 34-year-old Aguilera, of Newburgh, New York, slipped to 21-11 (14 KOs).

Sanchez fought for the first time since he knocked out Mexico’s Julian Fernandez (14-3, 11 KOs) in the seventh round December 19. Sanchez fought through a right ankle injury that night that nearly caused him to pull out of that bout on the Alvarez-Callum Smith undercard at Alamodome in San Antonio.

Sanchez had hoped to record another knockout Saturday night, but Aguilera took a knee with 1:21 to go in the sixth round after Sanchez hit him behind his head. Aguilera fell to his side and fell down again as he tried to get up.

He took a long time to try to recover and was examined by a ringside physician before their fight was abruptly brought to a halt. The crowd booed Aguilera loudly, apparently because they didn’t believe he was all that hurt by Sanchez’s unintentional foul.

Sanchez landed a right to the side of Aguilera’s head a little less than minute into the fifth round. They traded right hands with about 1:15 to go in the fifth round.

Sanchez also hit Aguilera with two right hands in the final 10 seconds of the fifth round, which made Aguilera hold him.

Sanchez connected with a right hand that got Aguilera’s attention about a minute into the fourth round. Another right hand by Sanchez landed with just under 50 seconds to go in the fifth round.

About 35 seconds into the third round, Aguilera complained that Sanchez hit him behind his head. While Aguilera turned toward Perez, Sanchez blasted him with a right hand that buzzed Aguilera.

Sanchez backed up Aguilera with a right hand just after the halfway point of the second round. Sanchez was aggressive as soon as their fight started and pressured Aguilera during a largely uneventful first round.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.