Alex Karras has always tackled life—if not opposing ball carriers—with humor. Although a savage All-Pro defensive tackle with the Detroit Lions, Karras was a practical joker off the field who rarely took anything seriously. That included his suspension from football for betting on his own team. His friends called him "The Mad Duck."

Four years ago Karras, now 40, left the Lions and went Hollywood. He had been bitten by the acting bug during the filming of George Plimpton's book about the Lions, Paper Lion. Karras did commercials, sportscasting and landed a few parts. In Blazing Saddles, for instance, he slugged a horse, which fell like a sacked quarterback.

His most important role was that of George Zaharias in the TV movie Babe, opposite Canadian-born Susan Clark. He went all out, convincingly. "I'm a Greek," Karras told director Buzz Kulik. "I know the guy (Zaharias) and what he feels. That's me." Susan Clark agreed, citing the scene in which the famed woman athlete dies of cancer. "When he played it every member of the crew wept. He's a terrific actor!"

Then Hollywood took over. Alex and his co-star, a divorcée, began playing for real. "Before too long, they were dating and then you could see it blossoming," recalls Babe director Kulik. "You could see they were more than just pals working together."

Soon Karras and Clark, who has said they have a very special friendship, were making the rounds. Accompanied by Susan's mother, they showed up at last month's TV awards show, where Clark won an Emmy for her role in Babe. Meanwhile, back in Bloomfield Hills, Mich., Ivalyn Joan Karras, Alex's college sweetheart at the University of Iowa, his wife of 18 years and mother of his five children, aged 2 to 16, brought a no-fault divorce action. She asked for custody of the children and for the Michigan house.

"Alex is doing his own thing," shrugged a Michigan friend, "and he always has. Joanie can't relate to his new image." Most surprised were his old teammates, who claim Karras was no "rounder" (fool-arounder). "After all, Alex wasn't the best looker," says one. "Even with a fistful of $50s, he didn't look too good."

Karras naturally disagrees. He once claimed to hate "All-American boy" types: "Quarterbacks always fit that category. I tried to wipe out as many of them as I could." And he added, "The casting people have stopped being hypocritical. Lots of people like a fat guy with glasses." The role he plays best is on ABC's Monday Night Football: "Just a fat Midwestern Greek—the guy who should have opened a restaurant in Des Moines."

But for all his bravado, Karras is hurting. With Susan Clark and her mother, he is off on a tour of Fiji and Australia to promote Babe for movie-house showings. "His personal life is traumatic," says Karras's manager. "He's a sensitive guy and won't say anything. That's why he decided to go on this tour."