Tonight at 10 p.m. EST on HBO, from the Scottrade Center in St. Louis, Devon Alexander and Marcos Maidana both step up to the 147-pound division for a 10-round main event. Sky Sports in the UK will also be televising. Bad Left Hook will have round-by-round coverage.

Maidana (31-2, 28 KO) still holds the WBA junior welterweight title (the "regular" belt), and isn't giving that up, but ex-junior welterweight titlist Alexander (22-1, 13 KO) is making the firm move to 147 pounds, following some struggles in his final three fights at 140.

This is also notable as Alexander's first fight under the Golden Boy Promotions banner, after leaving Don King last September and signing with Golden Boy during Mayweather vs Ortiz weekend.

In the HBO co-feature, Adrien Broner (22-0, 18 KO) defends the WBO super featherweight title against Eloy Perez (23-0-2, 7 KO). Broner is pretty heavily favored to retain in his fourth fight on HBO, where he's become an emerging young star to watch.