They've trained together, competed against each other, even braved the Rookie of the Year banquet circuit together.

But this Sunday, for the first time, NFL rookie phenoms Adrian Peterson of the Minnesota Vikings and Patrick Willis of the San Francisco 49ers will be teammates in earnest as they represent the NFC in the 2008 Pro Bowl.

Peterson, winner of the Associated Press NFL Offensive Rookie of the Year and Diet Pepsi NFL Rookie of the Year awards, will be the starting running back. Willis, the AP NFL Defensive Rookie of the Year, will play behind Seattle's Lofa Tatupu at inside linebacker.

Close friends since they prepared for the 2007 NFL Combine together at Athlete's Performance in Tempe, Ariz., Peterson and Willis turned heads this season with their precocious play.

For their respective teams, both of which struggled this season, their breakout performances were a shot of much needed good fortune — not surprising, perhaps, given their first-round draft positions: Peterson went No. 7; Willis, No. 11.

In their first seasons, Peterson and Willis established themselves not just as two of the most productive prospects in their class, but two of the best at their position throughout the league.

Peterson's rare combination of speed, power and grace have drawn comparison's to Gale Sayers and O.J. Simpson among others.

Despite splitting carries with Chester Taylor, Peterson finished the season with 1,341 rushing yards — second only to San Diego's LaDanian Tomlinson (1,475) — with 12 touchdowns, despite missing two weeks with a sprained knee.

In fact, in their only meeting of the season, it was Peterson who outperformed Tomlinson. While Tomlinson managed just 77 yards of total offense and a touchdown, Peterson exploded for 296 rushing yards and three touchdowns, breaking Jamal Lewis' single-game rushing record of 295 yards. (He also caught a pass for 19 yards.)

Minnesota won the game 35-17.

Peterson choked up as he received his Diet Pepsi Rookie of the Year Award.

"It means a lot," Peterson told ESPN afterward. "Coming into the season, I set my goals high. Some people said they were crazy or out of reach, but with the determination I brought and the effort of the whole team, I was able to accept this award."

Willis, who garnered 48 of 50 defensive rookie of the year votes, didn't receive quite as much national attention as Peterson, but his accomplishments weren't lost on diehard fans and the NFL fraternity.

All Willis did in his first season was lead the league with 174 tackles. He also had four sacks, two forced fumbles and five deflections. He was the only rookie named to the AP All-Pro squad.

As football fans have come to learn, the loquacious but humble Willis is equally impressive off the field. With both parents absent for long stretches, Willis took responsibility for raising his three younger siblings for much of their early lives.

"We're all capable of making that decision, whether you're young or old, to change your life and decide what you want to be about," Willis told ESPN's Jim Rome. "For me, it was doing right for my brother and sisters."

The four were eventually taken in by foster parents Chris and Julie Finley, and Willis would go on to star for Ole Miss, earning the Dick Butkus award as the nation's top linebacker.

Yet, Willis' yes-sir/no-sir interviews belie the unrefined aggression with which he pursues ballcarriers on the field. Though somewhat undersized at 6-foot-1 and 242 pounds, Willis has learned to maximize his explosive athleticism (Peterson calls Willis a "freak") under the tutelage of former Chicago Bears defensive captain and current 49ers assistant head coach for defense Mike Singletary.

Willis' athletic gifts were on full display in Week 12 when Arizona wide receiver Sean Morey caught a pass and took off down the right sideline toward the end zone in a play during overtime. Willis, who started inside, ran down the 5-foot-11, 193-pound Morey and prevented the likely touchdown. Arizona would eventually miss a field goal and the 49ers won the game.

At the Diet Pepsi Rookie of the Year Awards ceremony, Willis recalled the Dec. 9, 2007, game when he and Peterson finally had a chance to square off against each other.

Willis managed to take down the elusive Peterson with a solid hit, but Peterson was unfazed.

"As a defensive person, you hate to give a good hit and see the person get up like it was nothing," Willis said. "When I saw him bounce back up, I thought, 'Yeah, he's legit.'"

So legit, in fact, that Willis didn't seem to mind losing to his friend for the Diet Pepsi award.

"I have a lot of respect for Adrian," Willis told ESPN. "I'm really glad (he won). He's a very deserving person for this award and it couldn't have gone to a better person."

Reach Michael Tsai at mtsai@honoluluadvertiser.com.