LAS VEGAS - In the days of Muhammad Ali, George Foreman and Sugar Ray Leonard, sports fans could tune in during primetime on network television and catch the greatest sports stars of the day in the biggest events in the world, without it costing them a cent.

With NBC bringing fights back to primetime network television, the glory days of boxing are making a comeback. NBC's last primetime bout took place in 1985 when Larry Holmes defended his heavyweight world championship against Carl Williams.

The matchups taking place on March 7 featuring Keith Thurman vs. Robert Guerrero and Adrien Broner vs. John Molina Jr. harken back to the days when boxing dominated the sports world with Hall of Famers like Sugar Ray Leonard and Tommy Hearns.

Before Leonard became a household name, boxing on television began humbly on June 1, 1939 when NBC aired a bout that featured Lou Nova defeating Max Baer at Yankee Stadium.

Eventually NBC created a weekly series that ran on Friday nights called Cavalcade of Sports that ran on the network from 1946-1960. Cavalcade of Sports captivated sports fans, averaging about 17 million viewers for each fight with viewership peaking at 50 million people and a 24.8 share of all televisions.

CBS was also delivering primetime boxing with their Pabst Blue Ribbon Bouts on Wednesday nights. This series ran from 1948-1955 and averaged a 24.1 share through the duration of the series.

When ABC began featuring boxing on their Wide World of Sports series, they were able to give a young Muhammad Ali the national exposure he would need to become one of the most famous men in American history. The first heavyweight title fight they ever aired saw Ali, who went by Cassius Clay at the time; defeat the current champion Sonny Liston with a seventh-round knockout.

Ali and George Foreman's fight from Zaire, also known as the "Rumble in the Jungle", took place in 1975 and is still to this day the second highest-rated show in Wide World of Sports history. Ali's power to pull people on national television never wavered as his 1977 fight with Earnie Shavers was aired live on NBC and drew a 37.3 rating and a 57 share, the highest rated program for that week.

Even past the Ali-era, boxing continued to shine on national television. Leonard became one of the staples who built their fan base through the national television outlets, dating all the way back to his first professional fight, which, aired on CBS in 1977.

In 1979 ABC televised Leonard vs. Wilfred Benitez, marking the first time in 15 years that a fight below the heavyweight division was showcased in a primetime spot. In 1980, a Holmes title defense on ABC featured a bout with Leonard and drew a 25.8 rating and a 41 share, with an estimated audience of 55 million viewers.

It is reported to be the most-watched fight that did not involve Ali. Making the ratings even more impressive, and proving the crossover appeal of boxing in this era, was that the card went up against such iconic shows as "Little House on the Prairie", "M*A*S*H" and "WKRP in Cincinnati".

Boxing would still make appearances on national television but the regularity died down as fighters began to take their talents to pay-per-view events. December 1995 saw one of the last major fights on primetime national television when Mike Tyson's comeback fight against Buster Mathis Jr. was aired on the FOX Network. The show did a 16.1 rating with a 28 share and contributed to FOX's highest-rated night ever in primetime, with an estimated 43 million viewers.

Recent years have seen the occasional bout make its way to national television, but never in a primetime spot. CBS aired an afternoon world title match in 2012 between Leo Santa Cruz and Albert Guevara. The network hadn't aired live boxing since a 1997 bout between Bernard Hopkins and Glen Johnson.

Now, boxing returns with a new zeal and a full stable of great champions set to go toe-to-toe and lay it all on the line to give sports fans what they have wanted for so long.

A new era of boxing has arrived and on March 7 fight fans around the country will be able to get the first look at the next generation of boxing stars.

PBC on NBC on Saturday, March 7 at the MGM Grand Garden Arena is promoted by Goossen Promotions and features Keith Thurman vs. Robert Guerrero and Adrien Broner vs. John Molina, Jr. that will air live on NBC (8:30 p.m. ET/5:30 p.m. PT).

The Abner Mares vs. Arturo Santos Reyes bout will be televised live on Saturday, March 7, on the NBC show (8:30 - 11 p.m. ET) or on the NBCSN telecast (11 p.m. ET).