Now that middleweight titlist Gennady Golovkin is safely through his Saturday fight -- having absolutely drilled Nobuhiro Ishida in the third round in a knockout-of-the-year candidate -- attention can turn to a more serious fight for the man called “GGG.”

Golovkin (26-0, 23 KOs) is slated to be back in action June 29 at a site to be determined (likely on the East Coast) to headline an HBO tripleheader. He will be making his eighth title defense and fighting for the third time already this year. Golovkin’s opponent will likely be the one I have been hoping it would be (and the one HBO wants): Great Britain’s Matthew Macklin (29-4, 20 KOs).

Promoter Lou DiBella said both fighters have accepted the bout, and he is working to finalize the details with K2 promoter Tom Loeffler.

I see no possible way this can’t be an exciting fight. Golovkin is one of the most fan-friendly fighters on the planet and is in such a groove right now it is scary. Macklin is a quality contender who is also a regular crowd pleaser.

Although Macklin is just 1-2 in his last three fights, let’s go beyond the record. In June 2011, he lost a split decision in a world title fight to Felix Sturm on Sturm’s turf in Germany. Macklin was robbed, simple as that. He won, and did so rather easily in my view, but was absolutely ripped off.

His performance against Sturm was so good that it got him a shot at Sergio Martinez, the legitimate 160-pound champion. They met in March 2012 at the Madison Square Garden Theater in New York and produced a compelling and competitive fight. Macklin dropped Martinez in the seventh round before being stopped in the 11th round. Then, in Macklin’s ring return, he starched former junior middleweight titlist Joachim Alcine in the first round on the Martinez-Julio Cesar Chavez Jr. undercard last September.

Macklin is a worthy opponent for Golovkin, who has not had any other top middleweight contenders or titleholders show a willingness to face him. So props to Macklin for taking the fight a few months after he and Golovkin went back and forth a bit on Twitter about the proposed fight. Now DiBella and Loeffler are finishing a few details, DiBella said.

The two other featured fighters on the card are supposed to be Cleveland junior middleweight Willie Nelson (20-1-1, 12 KOs), who is on a very nice run and looking quite formidable, and super middleweight contender Thomas Oosthuizen (21-0, 13 KOs), a lanky lefty from South Africa.

Nelson, who is starting to win me over, doesn’t have an opponent yet. He has beaten three solid opponents in a row. He is coming off a blazing first-round destruction of Michael Medina on March 1. But before that, he upset John Jackson (one of former champ Julian Jackson’s sons) on the Martinez-Chavez Jr. undercard and also outpointed former Cuban amateur standout Yudel Jhonson.

Oosthuizen is my kind of fighter. He has skills and size (and a good chin) but is also more than willing to take two shots to give one. He’s a crowd pleaser.

DiBella and promoter Dan Goossen are trying to close the deal to match Oosthuizen and Brandon Gonzalez (17-0, 10 KOs), of Sacramento, Calif. Gonzalez recently withdrew from an April 12 ESPN2 undercard fight because of a hamstring problem, but he is expected to be just fine to lace 'em up for June 29.