Welterweight world titleholders Errol Spence Jr. and Shawn Porter have talked about their desire to unify belts and now they will get their chance -- against each other in a highly significant fight.

They will square off on Sept. 28 at Staples Center in Los Angeles in the main event of a Premier Boxing Champions card on Fox Sports pay-per-view, organizers announced at a news conference on Saturday at the MGM Grand, hours before another highly significant welterweight world title bout between Manny Pacquiao and Keith Thurman.

The much-anticipated Spence-Porter showdown was signed in April, just weeks after each had won their most recent bouts, but it took time to finalize the date and location. The winner could face the Pacquiao-Thurman winner next year.

The co-feature was also formally announced and not unexpected. It will match super middleweight world titlist Anthony Dirrell in a mandatory defense against former world titleholder David Benavidez.

Dan Rafael

ESPN Senior Writer