More than 500,000 viewers watched Joe Smith Jr.’s close championship victory over Maxim Vlasov on Saturday night.

Nielsen Media Research released statistics Tuesday that indicated an average of 506,000 viewers watched Smith’s 12-round, majority-decision win versus Vlasov in a WBO light heavyweight title fight on ESPN. Viewership peaked at 541,000 toward the end of ESPN’s main event from Osage Casino Hotel in Tulsa, Oklahoma.

ESPN’s entire one-hour, 51-minute broadcast drew an average of 436,000 viewers. The opener of the network’s two-bout broadcast – heavyweight prospect Efe Ajagba’s spectacular, one-punch, third-round knockout of Brian Howard – attracted an average audience of 323,000.

Nielsen’s numbers account only for viewers who watched the Smith-Vlasov doubleheader live on linear television. Viewers who watched on ESPN+, the network’s streaming service, aren’t included in the aforementioned figures.

Nielsen doesn’t track viewership for streaming services. ESPN doesn’t release streaming numbers, nor do its competing platforms in boxing, namely FOX and Showtime.

The 31-year-old Smith (27-3, 21 KOs), of Mastic, New York, edged Vlasov (45-4, 26 KOs), of Samara, Russia, on two of three scorecards to win the vacant WBO light heavyweight title.

Judges Gerald Ritter (115-112) and Pat Russell (115-113) scored their thoroughly competitive fight for Smith. Judge David Sutherland scored their back-and-forth fight a draw, 114-114.

Smith fought through swelling under his left eye and rallied in the final two rounds to narrowly win the fight and became a world champion.

Bob Arum, whose company co-promotes Smith and unbeaten IBF/WBC champ Artur Beterbiev (16-0, 16 KOs), will now try to put together a title unification bout between Smith and the unbeaten Russian knockout artist.

In the previous bout ESPN aired Saturday night, the 6-feet-6, 239½-pound Ajagba blasted Howard with a right hand that knocked his 40-year-old opponent unconscious. Referee Tony Crebs stopped their scheduled 10-round fight as soon as a twisted Howard hit the canvas awkwardly, at 1:29 of the third round.

The Nigerian-born Ajagba, a 2016 Olympian, improved to 15-0 and produced his 12th knockout. Howard (15-5, 12 KOs), of Loganville, Georgia, lost a second straight bout by knockout and is 2-4 in his past six fights.

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