LOS ANGELES – Luis Arias was supposed to keep busy Sunday against veteran Vaughn Alexander.

This time, though, it was Alexander who pulled off an upset in their 10-round middleweight match. Devon Alexander’s older brother produced perhaps the biggest win of his career, a split-decision victory over Arias on the non-televised portion of the Gervonta Davis-Isaac Cruz undercard at Staples Center.

Las Vegas’ Arias, who is promoted by Floyd Mayweather’s company, upset Jarrett Hurd in his previous fight. He looked lethargic against Alexander (16-6-1, 9 KOs), who withstood Arias’ success in the first few rounds and took control during the second half of their fight.

The 35-year-old Alexander appeared to be in better condition. St. Louis’ Alexander, who has fought mostly within the super middleweight division, also landed the harder, more effective punches for much of their fight.

Judges Jerry Cantu and Tom Carusone both scored the fight 96-93 for Alexander. Judge Tiffany Clinton scored it 96-93 for Arias.

Arias (19-3-1, 9 KOs) fought for the first time since he upset Hurd (24-2, 16 KOs), a former IBF/IBO/WBA 154-pound champion, by split decision on the Floyd Mayweather-Logan Paul undercard at Hard Rock Stadium in Miami Gardens, Florida.

Arias seemingly needed a knockout to win during the final round.

Alexander, who has been stopped just once, continued to land the harder punches throughout the 10th round. An accidental clash of heads caused Reiss to call a brief timeout to allow Arias to recover.

Arias landed two right hands in combination early in the ninth round. Arias initiated clinches during several other instances later in the ninth round, though he tried to work to Alexander’s body at times.

Alexander landed a right hand that made Arias retreat just before the ninth round ended.

Alexander was the aggressor and was effective enough to win the seventh and eighth rounds, when a seemingly fatigued Arias fought almost exclusively off his back foot. Alexander continued to out-work Arias during a sixth round in which he landed several hard right hands on the inside.

Reiss deducted a point from Arias late in the fifth round for repeatedly landing low blows.

Arias connected with a right uppercut that moved Alexander backward early in the fourth round. Alexander drilled Arias with a right uppercut of his own later in the fourth round, and then a thudding right to the side of Arias’ head.

Arias missed with a wild right hand in the third round, which left him in a vulnerable position. Alexander capitalized by landing a right uppercut that made Arias move away from him.

Arias landed several right hands during the second round and backed Alexander into the ropes. After backing Alexander into a neutral corner, Arias then landed a low blow that drew a warning from Reiss and caused a brief break in the action.

Arias got off to a strong start in the opening round, as the more aggressive, busier fighter.

Keith Idec is a senior writer/columnist for krikya360.com. He can be reached on Twitter @Idecboxing.