Mike Alvarado, Robson Conceicao, Mikaela Mayer to fight on June 30

A former world titleholder and a pair of 2016 Olympians head up the undercard of the Top Rank Boxing on ESPN show on June 30, Top Rank announced on Friday.

Appearing on the card at the Chesapeake Energy Arena in Oklahoma City will be former junior welterweight world titlist Mike Alvarado, Brazilian gold medalist Robson Conceicao and Team USA female lightweight Mikaela Mayer.

The previously announced main card is headlined by super middleweight world titlist Gilberto "Zurdo" Ramirez making his fourth defense against Roamer Alexis Angulo with junior welterweight contender and Oklahoma City's own Alex Saucedo taking on former lightweight world title challenger Lenny Zappavigna in the 10-round co-feature.

The ESPN telecast of the main card begins at 9 p.m. ET, and the entire card will stream live on ESPN+ beginning at 6 p.m. ET.

Alvarado (38-4, 26 KOs), 37, of Denver, will face Martin Martinez (18-14-1, 11 KOs), 27, of Mexico, in a scheduled 10-round welterweight bout.

Alvarado, who has been in numerous grueling fights and is on the backside of his career, has won four fights in a row against lesser opposition and still harbors hopes of another major fight.

"I've been reconstructing my entire organization over the past three years. I am training now with one of the finest professors of the sweet science, Tony Aguilera," said Alvarado, who will be coming off a 10-month layoff. "I'm excited to showcase what I've stayed dedicated to working hard for. Come June 30, I'll be one step closer to securing my legacy against anyone who stands in my way."

Conceicao (7-0, 4 KOs), 29, will square off with Ecuador native Gavino Guaman (5-2, 1 KO), 26, in an eight-round junior lightweight bout.

"I am very confident of fighting in OKC. I'm having a great high-level training camp in Miami," Conceicao said. "I'm evolving every day, and I'm sure I will put on a great show for all the fans." Mayer (5-0, 3 KOs), 27, of Los Angeles, will face Sheena Kaine (5-0, 1 KO), 33, of Edmonton, Canada, in a six-round lightweight match.

"I'm really excited to be fighting alongside the champ, Zurdo Ramirez," Mayer said. "Top Rank continues to put me on amazing cards with the best talent in boxing. Fighting in Oklahoma City is the perfect opportunity to meet more boxing fans and give them an exciting show as I continue my journey to a world championship."

The card will also include heavyweight Trey Lippe Morrison (14-0, 14 KOs), 28, of Tulsa, Oklahoma, against an opponent to be determined. Lippe Morrison, the son of the late heavyweight star Tommy Morrison, will be fighting for the second time since a hand injury kept him out of the ring in 2017.