LOS ANGELES – Robert Guerrero promised he would stick to boxing Saturday night.

That’s mostly what he did throughout an uneventful, 10-round victory over Gerald Thomas on the Errol Spence Jr.-Shawn Porter undercard at Staples Center. Until Thomas pressured him during the final two rounds, the veteran southpaw effectively worked off his jab and clearly out-boxed his unknown opponent on his way to winning a unanimous decision.

Two judges – Edward Hernandez Sr. and Steve Morrow – scored nine of the 10 rounds for Guerrero (99-91, 99-91). The third judge, Kermit Bayless, scored eight rounds for the former four-division champion (98-92).

The 36-year-old Guerrero (36-6-1, 20 KOs, 2 NC), of Gilroy, California, improved to 3-0 since resuming his career last December 1 at Staples Center. He announced his retirement after suffering a five-knockdown, third-round, technical-knockout loss to Omar Figueroa Jr. in July 2017, but he launched a comeback later the following year.

Thomas, of St. Marys, Kansas, slipped to 14-2-1 (8 KOs).

Guerrero stunned Thomas with a right uppercut that stopped him in his tracks with about 45 seconds to go in the final round. Guerrero couldn’t capitalize on that momentum, though, and their fight went the distance.

Thomas applied pressure late in the ninth round, when he backed Guerrero into the ropes and fired shots at his head and body. Thomas caught Guerrero with a right uppercut less than a minute into the eighth round, a shot Guerrero acknowledged as he backed away.

Guerrero heard some boos during the fifth and sixth rounds, in which he kept his distance and out-landed the limited Thomas rather easily. He picked up the intensity late in the seventh round, when he landed several hard head and body shots on Thomas toward the end of it.

Guerrero controlled the third and fourth round largely with his jab. Thomas didn’t attempt many punches, but mostly missed when he did.

There wasn’t much action for most of the first two rounds. Guerrero finally began unloading left hands and body shots on Thomas in the final minute of the second round, which made Thomas retreat. 

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