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What: “Unitas”

Where: HBO, tonight, 10-11

HBO and NFL Films have teamed up for a captivating one-hour documentary on one of the fascinating sports legends of the 20th century, Baltimore icon Johnny Unitas. Maybe teammate and Baltimore Colt center Bill Curry sums up Unitas best when he says, “He came out of nowhere. He wasn’t highly drafted. He wasn’t wanted. He came and proved himself with no advance billing. He dragged himself and the league out of obscurity into something nobody could have imagined.”

Curry also says, “Unitas, something about that name.”

Something about that man too.

The documentary traces Unitas from his childhood in Pittsburgh, though his 18 years and three NFL titles with the Colts and his retirement in 1973 after a season with the San Diego Chargers--in which he started only four games--and through his life today.

Unitas was 5 when his father died, and as a child he had to shovel coal to help support himself and his mother. “It taught me that you have to work to get whatever you need to have,” he says.

The documentary opens with Unitas saying he told an eighth-grade substitute teacher that someday he’d be a professional football player. He says he doesn’t know why he said it.

Things didn’t look good when he went off to Notre Dame as a 5-foot-11, 130-something pound quarterback and was told he was too small. He ended up at Louisville and later was drafted by the Pittsburgh Steelers, but was cut. “I never got a damn chance,” he complains.

In 1955, while also working full-time in a steel mill, he led the semipro Bloomfield Rams to an undefeated season and earned a tryout with the Colts. He got the starting job in the fourth game of his rookie season when former Oregon standout George Shaw broke a leg.

Today, after several business failures, Unitas earns a living by making appearances at card shows. An elbow injury he suffered in an exhibition game in 1968 has left his right hand useless, and he awkwardly signs memorabilia with his left hand. He is battling the NFL for compensation.

Players from the legendary 1958 NFL championship game, in which Unitas was the star, were honored at this year’s Super Bowl. Unitas was a no-show, instead choosing to fulfill a commitment to a card show in Canada.

Unitas says he asked the NFL to pick up the tab for what he could make at the card show and was turned down. “I told them, ‘Very simple, I can’t do it,’ ” he says.

But what comes through in this excellent show more than anything else is that Johnny Unitas truly was a legend and that, as Curry says, his image was matched by his substance.

Other playdates are Dec. 12, 9:45 a.m.; Dec. 16, 7 p.m., Dec. 21, 8 a.m. and 9:45 p.m.; Dec. 27, 11:30 a.m., and Dec. 27, 1 p.m.