By Ryan Burton

NEW YORK  - WBA Welterweight World Champion Keith "One Time" Thurman will defend his title against former champ "Showtime" Shawn Porter in a blockbuster matchup of two of the world's best 147-pound fighters on Saturday, March 12 on SHOWTIME CHAMPIONSHIP BOXING on CBS.

The welterweight showdown will air live on CBS at 8:30 p.m. ET / 5:30 p.m. PT from Mohegan Sun Casino Resortin Connecticut. The event, promoted by DiBella Entertainment, is produced by SHOWTIME Sports® for the CBS Television Network, both divisions of the CBS Corporation. The last primetime boxing event on CBS was Muhammad Ali-Leon Spinks on Feb. 15, 1978.

Thurman (26-0, 22 KOs), of Clearwater, Fla., and Porter (26-1-1, 16 KOs), of Las Vegas by way of Akron, Ohio, are both coming off superb 2015 campaigns that solidified the fresh faces among the elite of arguably boxing's most exciting division.  With perennial pound-for-pound champion Floyd Mayweather now retired, the 27-year-old Thurman and the 28-year-old Porter are hungry to stake their claim as the future of boxing.

 "One Time" Thurman, who owns a better than 80 percent KO ratio and knocked out 18 of his first 20 opponents, is considered one of the most avoided fighters in boxing.  After unsuccessfully lobbying to fight the best of the division for the past two years, Thurman finally had a breakout 2015.

The hard-hitting Florida native floored former champion and long-time contender Robert Guerrero en route to a convincing 12th round unanimous last March in Las Vegas.  He then dominated and bloodied former champ Luis Collazo on July 11, winning via seventh round TKO.  Thurman won the Interim WBA belt with a knockout of Diego Chaves in 2013 and scored consecutive knockouts over Jesus Soto Karass (2013) and Julio Diaz (2014) in his first and second title defenses.

Against Porter, Thurman will now get a chance to prove what he's been claiming for years - that he's the world's best welterweight - in the toughest test of his career.

"Showtime" Porter has built one of the most impressive resumes in the division since making his welterweight debut in 2010.  Porter, who surprisingly turned professional as a super middleweight (168 pounds), won the IBF crown in 2013 with an impressive unanimous decision over Devon Alexander.

The physically-gifted and offensive-minded Ohio native knocked out former two-division world champion Paulie Malignaggi with a brutal clean right hand in April of 2014 in the lone defense of his title.  Porter lost the IBF belt less than four months after the Malignaggi victory in a close majority decision defeat to undefeated British superstar Kell Brook, but he bounced back with a fifth-round knockout of Erick Bone in March of 2015. Porter scored what many considered an upset victory in his next bout over then three-division world champion Adrien Broner with a clear unanimous decision last June 20 in Las Vegas.

The aggressive, come-forward Porter has built his career as a perennial underdog who relishes in the role. But, with the resume he has built, it's hard to consider him an underdog anymore heading into this crossroads showdown with Thurman.

Tickets for the live event, which is promoted by DiBella Entertainment, are priced at $300, $150, $75 and $35 (plus applicable fees) and Ticketmaster are on sale now. Ticketmaster customers may log on to ticketmaster.com; call (800) 745-3000; or visit any Ticketmaster outlet. Tickets will also be available at the Mohegan Sun Box Office starting Saturday, January 23, subject to availability.