Former world middleweight king Bernard Hopkins will fight former undisputed light heavyweight champion Antonio Tarver in Atlantic City on 10 June.
Hopkins' last fight could be against Tarver
Hopkins, 41, ruled at 160lb for more than a decade before losing twice to Jermain Taylor last year.
Tarver, 37, is a two-time world champion at 175lb and has beaten the great Roy Jones twice in recent years.
The light heavyweight encounter makes it unlikely that either will meet super middleweight king Joe Calzaghe in July.
Calzaghe's promoter Frank Warren still has a raft of options available, with former four-weight world champion Jones top of his wish list.
The match against Tarver could be Hopkins' last fight. He has lost just four of his 52 professional encounters and defended his world middleweight crown 21 times.
Tarver has lost three of his 27 fights and has long been talked of as a potential opponent for Wales' IBF and WBO champion Calzaghe.