Tony DeMarco, once the welterweight champion of the world, will walk into the Portland Expo on Wednesday to help introduce the return of professional boxing at the facility, which will seem familiar to him. DeMarco fought twice at the Expo more than 50 years ago.

Bob Russo of the Portland Boxing Club will announce a mixed professional-amateur fight card featuring lightweight Ryan Keilczweski (17-0) of Quincy, Mass., and middleweight Russell Lamour (5-0) and bantamweight Jorge Abiague (3-0), both of Portland.

Brandon Berry (3-0) from the tiny Kennebec River valley town of West Forks will be matched in a lightweight bout.

Kielczweski, 24, most recently knocked out previously unbeaten Miguel Soto (11-0, 11 KOs) on an ESPN fight card in Salem, N.H., in July. He is managed by Lou DiBella, the former promoter of HBO fights.

DeMarco grew up in Boston’s North End and would walk to the old Boston Garden for his fights during the peak of a pro career. He fought 71 times, winning 58 — 33 by knockout — with 12 losses and one draw. He won the world weightweight title in 1955, beating Johnny Saxton on a 14th-round TKO.

It was a time when there was just one sanctioning body and eight weight divisions.

DeMarco lost his first title defense to Carmen Basilio later in 1955 on a 12th-round TKO. A rematch ended with the same result.

Lamour, a Deering High graduate, and Abiague, a Cuban native who came to America with his father and grandfather, both had long amateur careers at the Portland Boxing Club.

The news conference will start at 1 p.m. The public is invited.