Humberto Soto, Raymundo Beltran to square off June 27

Humberto Soto and Raymundo Beltran, ultra-experienced veterans known for fan-friendly fights, will square off in what appears to be a can't-miss battle June 27 at the StubHub Center in Carson, California.

The bout, agreed to Friday, will open the HBO broadcast headlined by the previously announced main event between Timothy Bradley Jr. and Jessie Vargas, who are meeting for a vacant welterweight world title.

The Soto-Beltran fight, while not yet official for a world title, likely will be for the junior welterweight belt currently held by Vargas, though he is expected to vacate before facing Bradley. That would clear the way for Soto and Beltran to fight for it. According to their promoters, both fighters will undergo random drug testing by the Las Vegas-based Voluntary Anti-Doping Association.

The fight will be another co-promotion between Soto's promoter, Golden Boy Promotions, and Beltran's promoter, Top Rank, once bitter enemies but now lovey-dovey since last year's reunion between Golden Boy president Oscar De La Hoya and Top Rank's Bob Arum, who promoted De La Hoya for most of his career.

"Adding this slugfest to the much anticipated slugfest between Bradley and Vargas just ensures another memorable night of prizefighting at the highest level at the StubHub Center," Top Rank vice president Carl Moretti told ESPN.com. "Those in attendance and watching at home on HBO are in for a special night with major implications for those combatants."

For Soto, the bout comes because of efforts by HBO Sports vice president Peter Nelson to find a fight for him. Soto was supposed to fight Frankie Gomez in the HBO co-feature of the Canelo Alvarez-James Kirkland card on May 9 at Minute Maid Park in Houston. However, Gomez was 6.5 pounds overweight at the weigh-in the day before, and the fight was canceled, which caused Soto, who was on weight, to lose out on a low six-figure payday.

Now Soto (65-8-2, 35 KOs), 34, of Mexico, a former lightweight and junior lightweight world titleholder, has another of those paydays to look forward to in an even more significant fight.

"We're excited about the fight. It should be a fun fight. Both guys are exciting fighters," said Golden Boy vice president Eric Gomez, who negotiated the bout with Moretti. "Peter Nelson took it upon himself to tell Soto they would have him back on after what happened with Frankie. We really appreciate it. He kept his word. He is doing the right thing here. Peter stepped up and said he'd get him back on the network, and he did it with what we think is going to be a great fight. Humberto Soto is going to make a war."

Soto is coming off an upset decision win against John Molina Jr. in September and has won seven fights in a row since being knocked out in the fifth round by Lucas Matthysse in 2012.

Beltran (30-7-1, 18 KOs), 33, a native of Mexico living in Phoenix, has had previous title opportunities. In 2013, he traveled to Scotland to challenge then-lightweight titleholder Ricky Burns and came away with a heavily disputed draw in a fight most thought Beltran won. Two fights later, he got a shot at Terence Crawford, who had beaten Burns to win the belt. But Beltran, who was one of Manny Pacquiao's main sparring partners for several years, was shut down and lost a virtual shutout decision.

After Crawford vacated the title to move up in weight, Beltran was scheduled to fight Japan's Takahiro Ao for the vacant belt May 1 in Las Vegas.

However, Beltran was 0.4 pounds over the 135-pound weight limit and could not win the title. The fight went ahead anyway, with only Ao eligible to win the belt, but Beltran knocked him out in the second round of a dominant performance, and the title remained vacant. Now Beltran is moving up in weight to take on Soto.