Gennady Golovkin's 8th defense set

Middleweight titlist Gennady Golovkin has defended his 160-pound belt seven times, but defense No. 8 will come against his most significant opponent so far, former two-time title challenger Matthew Macklin.

Golovkin and Macklin will meet June 29 in the main event of an HBO-televised tripleheader at the MGM Grand Theater at the Foxwoods Resort Casino in Mashantucket, Conn., promoter Lou DiBella announced on Wednesday in the culmination of a difficult deal that has been in the works with K2 promoter Tom Loeffler for the past few weeks.

It matches two of the best and most exciting middleweights in the world.

"Golovkin-Macklin is one of the very best fights that can be made in the middleweight division and all of boxing," DiBella said. "It figures to be a barnburner and we are thrilled that Matthew is getting another deserved opportunity at a world title. It's a great style matchup on paper. If somebody whacks somebody, it won't be a surprise because they are both brawling middleweights."

Golovkin (26-0, 23 KOs) is one of boxing's most aggressive crowd-pleasers and will be fighting for the third time already in 2013. He opened the year on Jan. 19 with a dominant seventh-round knockout of Gabriel Rosado in New York and returned on March 30 for a devastating third-round destruction of Japan's Nobuhiro Ishida in Monte Carlo, Monaco in what is a candidate for knockout of the year.

"I'm excited to return to the United States and once again fight on HBO," said Golovkin, 31, who is from Kazakhstan but lives in Germany and trains in California. "Matthew Macklin is a skilled, strong fighter and I look forward to the challenge. I have seen a few of his fights and am very conscious of how tough of a battle this is."

Said Macklin: "Golovkin hasn't put a foot wrong yet as a pro. He's destroyed pretty much everyone and, as a consequence, he's probably the most hyped fighter in the sport right now. People have made him out to be this monster, but he bleeds red just like everyone else and, for the first time in his career, he's going to be stepping into the ring against a big, strong, proper world-class middleweight."

Macklin also has a track record of being in exciting fights, but he is far more highly regarded than anyone Golovkin has faced.

"Gennady is excited to return to the ring so quickly to defend against a proven, top-rated middleweight in Matthew Macklin," Loeffler said. "Gennady was ringside for Macklin's fight against Sergio Martinez last March and saw firsthand how dangerous he is."

In 2011, Macklin lost a split decision challenging then-titlist Felix Sturm in Sturm's native Germany in a fight most believed Macklin had clearly won. In his next fight, in March 2012, Macklin gave world champion Martinez a very tough fight. Macklin knocked Martinez down in the seventh round and was competitive all the way until being stopped in the 11th round.

Macklin (29-4, 20 KOs), 30, an Irishman from England, rebounded from the defeats last September when he blew out former junior middleweight titlist Joachim Alcine in the first round on the undercard of Martinez's unanimous decision win against Julio Cesar Chavez Jr.

"When you compare my last three opponents to Golovkin's last three opponents, it's clear who the proven entity is going into this fight. I got robbed against Felix Sturm in Germany, it was nip-and-tuck between me and Sergio Martinez until I got caught in the 11th and last time out I blew away Joachim Alcine inside a round, a former world champ who was coming off a career-best win (against David Lemieux)," Macklin said.

In the co-feature, super middleweight Thomas Oosthuizen (21-0-1, 13 KOs) of South Africa will square off with Brandon Gonzalez (17-0, 10 KOs) of Sacramento, Calif., in a scheduled 10-round fight. The opening fight is not set yet but will involve junior middleweight Willie Nelson (20-1-1, 12 KOs) of Cleveland against an opponent to be determined.