Welterweight world titleholder Errol Spence Jr. has designs on major fights, including a potential unification showdown with two-belt titlist Keith Thurman Jr. in the fall, but there will be other business first.

Spence has been ordered to make his mandatory title defense against unbeaten, but virtually unknown, up-and-comer Carlos Ocampo.

On Saturday night at Barclays Center in Brooklyn, New York, Spence retained his 147-pound world title for the first time, as he ran roughshod over former two-division world titleholder Lamont Peterson. Spence knocked him down in the fifth round, swelled his eyes and battered him relentlessly in a totally one-sided fight until Peterson's trainer Barry Hunter stopped the fight one second into the eighth round.

Spence did not have long to savor the resounding victory. After spending most of his postfight news conference talking about his desire for a major fight and to unify titles against Thurman later in the year -- a nod to Thurman's desire for an April tuneup after being out of action for a year because of elbow surgery -- Spence was ordered on Monday to fight Ocampo next.

The International Boxing Federation sent Spence a letter, via promoter Tom Brown's TGB Promotions, ordering the bout. The letter pointed out that Spence's fight with Peterson was an exception to a mandatory defense that was approved with the condition that the winner of Saturday's fight must next face the leading available contender.

With the No. 1 and No. 2 positions in the IBF welterweight rankings vacant (because no elimination bout had taken place to fill either slot), No. 3 Ocampo is the leading available contender and, thus, Spence was ordered to fight him next.

The IBF ordered Brown and Ocampo promoter Zanfer Promotions to begin negotiations immediately. If the sides do not make a deal by Feb. 22, a purse bid will be ordered to determine promotional control of the bout.

In the event of a purse bid, Spence would be entitled to 85 percent of the winning bid, and Ocampo would get the remaining 15 percent, a smaller figure than had he fought an eliminator to become No. 1 or No. 2.

Ocampo (22-0, 13 KOs), of Mexico, has yet to face any top opponents, but many consider him an excellent prospect. His most notable victory came in November 2015 when he outpointed onetime prospect Jorge Paez Jr.

Spence (23-0, 20 KOs) said after the fight with Peterson that he wanted to fight three times this year and that he wanted his next fight, likely to be in May or June, to be a homecoming fight in Dallas, where a fight with Ocampo would make sense.