Terence Crawford already cleaned out two divisions. Now he’s coming for a third.

And if he’s successful, he will be the unquestioned pound-for-pound king.

That’s because the welterweight division is far and away the most talent laden in boxing, and Crawford made his move to 147 pounds official Thursday when the WBO installed him as the mandatory challenger to Jeff Horn, the organization’s champion.

Bob Arum told RingTV.com that he plans to match Horn and Crawford in either March or April on ESPN, as long as the Australian is successful during his December title defense against Gary Corcoran, whom Horn is heavily favored to beat. March 10 is the target date.

“Terence was having difficulty making 140 pounds; he had a nutritionist in the last fight and it looked like he might be a little overweight, but he made it because he’s a diligent guy,” said Arum, who would prefer to close a deal for them to meet in March rather than April as long as the Australian comes out “in good physical shape” following the battle with Corcoran. “But it was a real struggle, I think.”

If it was, it wasn’t evident on fight night. Crawford (32-0, 23 knockouts) knocked out Julius Indongo in Round 3 to become boxing’s first undisputed champion since 2006.

The Omaha, Nebraska, native also was dominant at 135 pounds, and he looks better every time out. Now, boxing fans should finally have the opportunity to see Crawford match wits with fighters who can also boast pound-for-pound status.

“First he has to beat Horn and win the title but once he does, then we’ll consider fights with Danny Garcia, (Keith) Thurman, all of those guys,” Arum said, referring to Al Haymon’s stable of elite welterweights, which also includes Errol Spence and Shawn Porter. “I don’t anticipate any difficulty in making them.

“We’re all in boxing, we’re all looking to build boxing and there will come a time when a promoter is putting on fights for Showtime and wants to use one of our fighters and we wouldn’t stand in the way. I think everybody now in boxing or most people in boxing are of the mindset to make the best possible fights.”

And perhaps the best possible fight that can be made is Crawford against Spence, a meeting of two of the best talents in the sport. That fight is a ways off, though.

After all, Crawford, 30, isn’t even yet a champion at welter. He first needs to top Horn (17-0-1, 11 KOs), who showed surprising physicality in the win over Manny Pacquiao. And Spence has yet to defend the 147-pound strap he won when he stopped Kell Brook over the summer. That will come when Spence fights Lamont Peterson in January.

That’s a bout that needs to be built properly, and if all goes according to plan, could be a marquee pay-per-view fight in 2019. In the meantime, Crawford is going to get his feet wet against the man who upset Pacquiao.

The welterweight division is officially on notice.

Mike Coppinger is the Senior Writer for RingTV.com. Follow him on Twitter: @MikeCoppinger