Could Floyd Mayweather lose for the first time in his career Saturday night?

Anything is possible, but is it likely?

ESPN.com boxing insider Dan Rafael called in from Las Vegas on Friday and said exactly that.

Mayweather is fighting an unknown of sorts in Robert Guerrero, a southpaw who has but one loss in his professional career on Saturday night.

But Rafael actually believes,although this was a hand picked opponent as all of them are that Guerrero could actually give Mayweather a bit of a challenge.

Mayweather is 43-0 and has hand picked his opponents and venue (Las Vegas) for much of the later stages of his career.

So what's on the horizon after this fight against Guerrero?

Mayweather signed a 6-fight contract with SHOWTIME this past year so five more fights are scheduled to happen after this weekend for Mayweather, but Rafael told Mike Gill and Todd Ranck that a much anticipated one with Manny Pacquiao wont happen.

Dan Rafael LIVE from Las Vegas: