Unbeaten featherweight Gary Russell Jr, scored a fourth-round knockout over Miguel Tamayo on Thursday night at Barclays Center in Brooklyn, N.Y.

Russell-Tamayo happened on the undercard of the Fox Sports 1 card topped by Victor Ortiz and Luis Collazo.

Russell said he was battling the flu, but he had no problems. He floored Tamayo (14-8-2, 12 KOs) with a vicious right hook that deposited him on his backside. Tamayo sat on his butt as referee Eddie Claudio counted him out. The end came at 1:04 of Round 4.

Russell (24-0, 14 knockouts) was coming off a unanimous decision over Juan Ruiz in August.

In October, Russell was declared the WBO’s mandatory challenger to Mexican titleholder Orlando Salido. Salido is scheduled for a defense against Ukrainian amateur star Vasyl Lomachenko on March 1.

Golden Boy CEO Richard Schaefer said that an offer for Russell to challenge WBC beltholder Jhonny Gonzalez was turned down by Gonzalez, who won the belt by a shocking first-round knockout  victory over three-division titlewinner Abner Mares  in August.

Mares suffered a rib injury, which scuttled a proposed Feb. 15 rematch with Gonzalez.