Amir Khan will be at ringside when Devon Alexander defends his welterweight title this weekend.

The British boxer will be a commentator for Showtime’s TV coverage of the card at Brooklyn's Barclays Centre in New York, replacing Paulie Malignaggi, the regular commentator who will be in the ring against Zab Judah in a main-event showdown of hometown heroes.

A deal was almost finalised before Khan decided against fighting Alexander for the IBF welterweight title amid speculation that he may be the next opponent for unbeaten Floyd Mayweather next May.

The Khan and Mayweather camps have said no such deal is in place, but neither fighter has announced a next opponent.

"They felt I was a big risk; that I was too much for him right now," said Alexander, who faces unbeaten American Shawn Porter instead on Saturday night.

“I was ready to fight him. He pulled out so it didn't happen that way."

Khan, a former light-welterweight champion, will handle guest analyst duties during the fight, as well as for the one between Judah and Malignaggi. Khan beat Malignaggi in 2010 and Judah in 2011.

"The main event between Paulie and Zab will be a Brooklyn blockbuster with two of the most skilled fighters in boxing. Having shared the ring with both, I know they will bring speed, power, ring craft and heart to the table," Khan said on Monday.

The Briton, who won a silver medal at the 2004 Athens Olympics when he was 17 years old, turns 27 on Sunday. He has a professional record of 28-3, with 19 knockouts.