OAKLAND -- A trial challenging the NCAA's ban against compensating student-athletes turned Thursday to the financial backbone of major college sports -- television dollars.

In the fourth day of the trial, dueling experts in the sports broadcasting industry offered competing views of whether paying college football and basketball players would spoil college sports and even diminish their value to the television networks that pay billions of dollars to broadcast everything from March Madness to the BCS championship bowl game.

Neal Pilson, former president of CBS Sports and a witness for the NCAA, said he has no doubt paying student-athletes would undermine college sports because viewers "differentiate it from professional sports."

"I have substantial concern it would change the fabric of the sport," said Pilson, who testified he has negotiated at least $15 billion in sports contracts in his career.

Chief U.S. District Judge Claudia Wilken is hearing the legal challenge to the NCAA's ban on allowing student-athletes to share in the profits from Division I college football and basketball. Former athletes have pressed a class-action lawsuit, seeking the right to collect a share from the massive profits in college sports, primarily from rights to television, video games and merchandise.

Wilken is deciding the case without a jury.

Edwin Desser, a sports television expert for the players who also has negotiated billions of dollars in sports contracts, including for the NBA, took a different view than Pilson. He told the judge that television contracts with college sports have no obstacle precluding paying players for the use of their images and names.

Dresser pointed out that broadcasts of major college sports rely heavily on promoting the players. And he testified that broadcasting college sports is part of the same "ecosystem" as professional sports.

"They are consumed by many of the same fans," Dresser said.

The trial resumes Friday with more witnesses from the players' side, including Chase Garnham, a former Vanderbilt linebacker expected to recount his football experience, including being required to sign forms permitting the university to use his image in promotional material.

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz