Ten years ago, before Super Bowl VII, George Allen said Dolphins running back Eugene (Mercury) Morris, No. 22, was the man to stop. So Morris, who went on to play in three successive Super Bowls and earned two citations in the Football Hall of Fame, acted as a decoy to fullback Larry Csonka in the 14-7 victory over the Redskins.

Today as the former All-Pro prepared to watch Super Bowl XVII on a 19-inch black-and-white television in his Dade County jail cell, the columns of sports copy left him out. Eight blocks away in the Orange Bowl during a recent tribute to the 1972-73 Dolphins, the man known for his darting, dancing moves wasn't mentioned. "It's par for the course--I'm incarcerated," said Morris, 36, in a pregame interview. "But do you think people forget?"

"That was the year Csonka and I were the first two backs in the history of the game to gain 1,000 yards for one team ," he said while lighting one of a chain of cigarettes. "We broke so many records." By his retirement in 1976, Morris had gained more than 4,000 yards and had averaged 5.12 yards per carry--a third-place National Football League record he still holds.

This year Morris received some new numbers: 20 years in prison, 15 without possibility of parole or early release under a get-tough Florida law, for trafficking in cocaine. He was convicted of selling 456 grams--slightly more than a pound--to an undercover agent last August.

He turned down offers to plead guilty in return for a waiver of the mandatory sentence, and he won't name other football players involved with cocaine. "As of this moment," he said emphatically, "I know of no one else in the NFL I could name with a regular, minor, existing or major problem with cocaine . . . I do not believe it is my job to collect people for witch hunts . . . What purpose is served, justice or headlines?"

Morris is broke. He's lost one Super Bowl ring and another was stolen. He considers the name "Mercury" a stigma--a source of his nostalgia and the fame that wouldn't fade. "If he'd just been Gene Morris," said his lawyer Ron Strauss, "no one would have cared," meaning the government.

Morris blames his fate on "a lackadaisical attitude about growing up," poor preparation for life after football and a string of bad luck. Now he's taking a lesson from the game. "I've got the ball and I'm behind, with the clock running down. My biggest Super Bowl--my appeal--is coming up." Morris is not eligible for bail.

Early this morning Morris was lying in his beige-and-brown cell watching TV and reminiscing. On the West Coast, it was five minutes to the Dolphins' curfew. He reviewed in his mind the pregame events--meetings, meals, coaches eyeballing players, Don Shula giving the first plays.

With a laugh, Morris anticipated Shula's locker-room speech verbatim, ending with "We want to come out on top." Morris wasn't taking bets but predicted a Dolphins win by seven to nine points.

The day he was busted Morris was set to coach his third season of Pop Warner football in South Miami, where his son Maceo is a running back with his father's number and his stepson Buck is a defensive tackle.

"The first year I coached them to a 6-2-2 record. I trained them with all the same plays as the 1972 Dolphins. They missed going to the Bowl by one point . . . I pushed Maceo like Shula pushed me." He hasn't heard from his old coach.

Reaching for a football metaphor, Morris describes his jail cell as another locker room. "Except you live there," he adds soberly.

His uniform is running shoes, jeans and a polo shirt barely restraining his biceps that are six inches across. At 180 pounds, he's about 20 pounds lighter than his playing weight. He is restless in this locker room, so he visits the jail law library searching for clues for freedom.

Morris shares his fifth-floor cell with 16 other inmates charged with felonies from murder to biting a police dog. There are two showers, two toilets, a small day room, a coffee pot and the television in their chamber. Morris has a corner bunk by the window. He seldom looks out.

"Dear Mercury," reads the fan mail from 9-year-old Shawn, "I hope you live until you get pass 100 years old. You are my best friend and will always be my favorite football player." The flip side shows No. 22 in his jersey: "You are always No. 1!"

"I get 30 to 50 letters a day," said Morris, thumbing through a stack delivered by his attorney. Some are religious; others are first-time communications with a stranger. He's heard from his fifth-grade music teacher and his best friend from sixth grade. Mothers want football tips for their sons.

Fans in Pittsburgh contributed more than $300 to help send Morris, his family and three police guards to his hometown for two days last week to visit his mother, who is dying of cancer. One $5 donation came from an unemployed steelworker.

Morris' eyes sparkled with genuine gratitude. Still cocky, mercurial, glib, he is mellowing.

"It's almost a charismatic type of environment here for me," he said. "Maybe it's because I don't feel like it's prison, because the bars aren't really holding me . . . I need no help to get me from day to day. I survive by my faith and what I know to be the truth"--that the top of the pile is at the bottom of the heap. "People always get behind the underdog."

He lit a cigarette and paced. The public attention keeps his cause alive. "This is not solely to benefit Mercury Morris or Eugene Morris, but a great deal of people who are programmed to come here and just do their time and accept it," he insisted.

"Possession I'm guilty of. Trafficking I'm not. I'm not a drug dealer." Morris' appeal revolves around entrapment--that he was an easy target in the government's toughness in the South Florida war on drugs. The government called it "opportunity."

"This is like playing football, only we're dealing with a quarter of life," he said. "The player runs out of bounds and throws a shoulder to a person on the sidelines. He's penalized 15 yards. Do you get 15 years in prison and thrown out of the game for a one-time mistake?"

Yet Morris pronounced his bust a "blessing." He admitted to using cocaine since 1973, although he said he stayed off during football season. Then came life in the Miami fast lane, where drugs are a "social grace." He was pinned by fallen business deals, pain from neck injuries and costly lawsuits for custody of a son, back football pay and damages from an auto wreck.

"Freebasing" cocaine was the escape. Morris wasn't deterred when his next-door neighbor, a heavy cocaine user, was found murdered and stuffed in a floating oil drum in 1980. Finally Morris sought counseling through television evangelist Pat Robertson's "700 Club." The Morrises began going to church last summer. "Two nights before the bust, I prayed I would be released from that bondage of drugs ," he said. His house was double-mortgaged and his phone bill was three months overdue. The government confiscated his Cadillac.

Does he miss drugs? "No. Are you kidding? Reality and priorities . . . forget it!"

This is the message Morris hammers at daily in jail to about 60 juveniles, ages 14 to 17, being tried as adults. "They are already members of a farm club for career criminals," Morris said. He tells them they still have a choice.

"He's able to relate to them and show a role model," said Russell Buckhalt, the jail's social services supervisor, who asked Morris to work with the youths. Buckhalt said he thought Morris was rehabilitated. "A lot of the counseling has to do with drugs. Though he's incarcerated and faces a long prison sentence, he's still a professional athlete--people look up to him."

What does the once All-Pro tell the juvenile offenders in that high-rise jail two tiers of clanging steel from freedom? "Don't start reading that book someone says 'don't touch,' because you know the ending."