Earl Campbell used the power in his legs to become one of the most prolific running backs in the college game and the NFL in the 1970s and '80s.
The strength of Campbell's voice at the University of Texas could prove to be one of the last shoes to drop for Mack Brown in 2013.
Campbell, speaking Sunday to KRIV-TV in Houston, said the time has come for Brown to step down as coach or be forced out at Texas.
"Nobody likes to get fired or leave a job, but things happen," Campbell said, according to the Fox affiliate. "I'd go on record and say yes, I think it's time."
Brown has long been a supporter of Campbell, who remains involved in the Texas program, still works out in its athletic facilities and meets with prospects during recruiting events.
"Earl has done so much for Texas," Brown said Monday at his regularly scheduled news conference in Austin. "He will always be welcomed at our school. I'm disappointed in his comments, but he's entitled to his opinion."
Before a 31-21 win over visiting Kansas State to open Big 12 play on Saturday, Texas (2-2) had lost two games in a row after posting three subpar seasons, putting Brown on the hot seat in one of the most coveted coaching jobs in the nation.
But Campbell thinks it's too little, too late for Brown to save his job.
"I'd just say this, I take my hat off for USC for what they've done," Campbell said of one of the other top jobs, left temporarily vacant Sunday after the Trojans fired Lane Kiffin. "They didn't mess around with it. They just said, 'Let's do it now.' I think at some point our university's people are going to have make a decision."
Former Texas quarterback Chris Simms also stepped forward Friday and said on a Fox TV show that he doesn't think Brown will return in 2014 and that Texas doesn't have the talent needed to save this season.
Brown, who is under contract until 2020 and will be paid $5.4 million this year, took Texas to the 2005 national title. The Longhorns advanced to the championship game after the 2009 season but lost to Alabama.
Brown has been adamant that he would not step down any time soon.
Texas next plays at Iowa State on Thursday (7:30 p.m. ET on ESPN).
The Longhorns are 24-18 since that loss to the Crimson Tide, and Brown, 62, was under fire from fans upset about a 1-2 start this year after consecutive lopsided losses to BYU and Mississippi.
"Some people get too old," said Campbell, the 1977 Heisman Trophy winner with the Longhorns and NFL Hall of Famer after an eight-year career with the Houston Oilers and, briefly, the New Orleans Saints. "If players get too old to play a game, why can't a coach get too old to coach it?"
Campbell even suggested Brown's replacement.
"If we're going to make a change, I would like to say that we got one in the house, Jerry Gray, who's getting in the College Football Hall of Fame," Campbell said of the former two-time All America defensive back at Texas, now the defensive coordinator of the Tennessee Titans. "I think that would be a good place to start."
Campbell said the decision to call for Brown's ouster didn't come easily.
"Very hard because Coach Brown is a very good man," Campbell said. "I just hope he doesn't stay. ... He's done some great things. The program, he brought it back, and we don't need it to get run down where somebody has to start all over again."
Information from Max Olson of ESPN.com and The Associated Press was used in this report.