Sports-crazy kids—especially boys—have allowed professional football players Tim Green, Tiki and Ronde Barber, and sports journalists Mike Lupica and John Feinstein to add “bestselling author” to their résumés. Assuming a mantle once worn by Matt Christopher, the middle-grade novels of these five authors have sold more than two million copies in the past few years.

“People told me bringing books to boys was an impossible feat, but I knew who those boys were because I was a boy who would have loved a Mike Lupica novel,” says Michael Green, who now edits Lupica at Philomel. “Following sports was how I developed my love of story.”

Many sports stars have dipped their cleats into publishing with inspirational picture books. The Barber twins moved into novels (the third, Wild Card, has just been released) after the success of their three autobiographical picture books (written with coauthor Paul Mantel). “One of our sales people said, 'You should grow these books up,' ” says Simon & Schuster editor Paula Wiseman. “It made perfect sense, because the whole idea of them writing for us in the first place was to create books boys wanted to read.”

With the exception of Feinstein's books, which feature a boy and a girl in the star roles, the audience is mostly male, though Philomel's Green suspects more than a few of the 1.2 million Lupica books sold have been to a “secret audience of fathers.” Unlike Christopher's stories, which were set on sandlots and in school yards, most of the new crop take readers behind the scenes at marquee sevents: Feinstein's latest, Change-up, has the Washington Nationals in the World Series; the young hero of Lupica's forthcoming Million Dollar Throw gets his chance at glory during halftime at a New England Patriots game.

“Definitely part of the appeal is that I'm going to take them to a place they're not going to get to otherwise,” says Tim Green, who spent eight years as a defensive back with the Atlanta Falcons before putting his English literature degree from Syracuse University to full use. Green had already made a name for himself with suspense novels when HarperCollins editor Barbara Lalicki called him after finishing one of his adult thrillers. “She asked for a page-turner for kids set in the sports world,” recalls Tim Green, a father of five who'd read Ella Enchanted, Holes and Bud, Not Buddy aloud to his own kids. “I fell in love with the idea immediately.”

Lupica's start came when his son got cut from the basketball team. To soothe Alex's broken heart, Lupica hired a coach and recruited other kids who'd been cut for the startup New Canaan Rebels. A friend said, in passing, “If this were a Disney movie, they'd beat the team they got cut from in the championship game.”

Lupica sniffed a story. His agent, Esther Newberg, told him to write a proposal. Based on a three-page outline, Travel Team sold to Green at Philomel that afternoon. The book spent 16 weeks on the New York Times bestseller list. “I just thought it was going to be a stocking stuffer for the kids on my team,” Lupica says.

The authors all say writing for this age group is the most satisfying work they've done.

It's also a deep well. “All the e-mails are, 'Please. When's the next one coming?' ” says Tim Green.

“This isn't like adults, where you can sell one book a year,” Lupica says. “The appetite is tremendous.” Million Dollar Throw (Philomel, Nov.) will be Lupica's 12th novel for young readers, including the six in his chapter book series, the Comeback Kids; his 13th, Bat Boy, is due next March.

The key, says Philomel's Green, is that the audience has been there all along—they're just not reading novels: “I wasn't a book reader as a kid, but it's wrong to say I wasn't a reader. I could not get enough about sports. My dream was to be the bat boy for the Mets.”