Shane Mosley will fight Andre Berto in a welterweight title unification fight on Jan. 30 in Las Vegas on HBO, it will be formally announced on Saturday.

Mosley, THE RING's No. 1-rated welterweight, had hoped to lure either Manny Pacquiao or Floyd Mayweather Jr. into the ring but must settle for the undefeated, but lesser-known Berto.

Mosley (46-5, 39 knockouts) is coming off a spectacular ninth-round knockout of Antonio Margarito last January but has been unable to make a big fight.

This is an important opportunity for Berto, whose reputation would receive a serious boost if he beats Mosley.

Berto (25-0, 19 KOs) is coming off a one-sided decision over Juan Urango in May.