CARSON, Calif. -- Welterweight Robert Guerrero returned from a 13-month ring absence with a bloody, bruising unanimous decision over Japan's Yoshihiro Kamegai on Saturday night.

Guerrero (32-2-1) hadn't fought since his one-sided loss to Floyd Mayweather Jr. last May. The former four-division champion was severely tested by the tenacious Kamegai (24-2-1), and both fighters took tremendous punishment in a draining slugfest.

Robert Guerrero returned from a 13-month ring absence and beat Yoshihiro Kamegai by unanimous decision. Stephen Dunn/Getty Images

Guerrero fought the second half of the bout with a grotesque cut and swelling on his left eye, but landed some of his biggest shots in the 12th round. Despite trading brutal punches throughout the night in the outdoor ring, yet neither recorded a knockdown.

"I feel into that banging again, and that's something I've got to work on," Guerrero said, his damaged eye concealed behind sunglasses. "I wanted to box on the outside, but I have a habit of banging away and exchanging."

Guerrero finished the thrilling main event with his left eyelid swollen and discolored next to a severe cut. Yet Kamegai was unable to exploit the advantage with his right hand, failing to finish the fight despite such a tantalizing target.

"He has a weird, awkward style, and he's strong," Guerrero said. "I'm not surprised, but he can take some shots. No disrespect, but look at the size of his head."

Judge Max DeLuca scored the bout 116-112, while Pat Russell and Tony Krebs both saw it 117-111. The Associated Press favored Guerrero 116-112.

Guerrero repeatedly knocked back Kamegai, but the Japanese fighter with virtually no North American profile kept coming forward. The fighters smiled and embraced after trading head shots at the final bell.

"I'm OK with the decision," Kamegai said. "He shook me a couple of times, and I felt weakened in the legs, but I think I had him hurt a few times, too, but he recovered very well."

Earlier at the StubHub Center south of Los Angeles, Vasyl Lomachenko won the WBO featherweight title in just his third pro fight with a masterful majority decision over Gary Russell Jr.

Devon Alexander won a wide unanimous decision over Jesus Soto Karass in Alexander's first bout since losing his welterweight title in December, and former light heavyweight champion Chad Dawson also won by first-round stoppage in his first bout after back-to-back losses and a yearlong break.

Lomachenko (2-1, 1 KO) battered the previously unbeaten Russell around the ring, showing off his skill and power while blocking the wide majority of Russell's punches. The Ukrainian star hurt Russell repeatedly in the late rounds, reaching the final bell while pounding on Russell in his corner.

Lomachenko is a two-time Olympic gold medalist who demanded an extraordinarily quick path to a title shot when he turned pro last year.

Alexander (26-2), the former two-division champion from St. Louis, looked sharp in his ring return from a decision loss to Shawn Porter. Using his speed and activity to neutralize Soto Karass' power, Alexander produced more action than in most of his recent fights while slapping around his slower opponent.

Two judges scored the bout 99-91 for Alexander, and a third favored him 97-93.

"There was no question in my mind who won this fight," Alexander said. "He was missing with most of his shots, but he caught me a couple of times. I'm my own worst critic, but I'm happy with this performance."

Dawson (32-3, 18 KOs) landed just eight punches and wasn't tested in his first fight since Adonis Stevenson seized his title belts with a first-round stoppage last June. George Blades, a 39-year-old journeyman, went down twice in the first round before the referee stopped it with 25 seconds left.

Dawson missed the 179-pound catch weight and had a 20-pound advantage over Blades by fight night. The two-time light heavyweight champion insists he's still a 175-pound title contender, attributing his weight problem to his ring absence.

Dawson wants to fight two more times this year.

"I'm right back in the gym," Dawson said. "I can't afford to take time off. This is the second chapter of my career, and hopefully the last."