In a long-term blow that could be as brutal to swallow as the Dolphins' loss Sunday, cornerback Will Allen will miss the rest of the season with a torn anterior cruciate ligament, team sources told The Miami Herald.

The Dolphins will start Vontae Davis in Allen's place. That means Miami will now have both of its rookie cornerbacks in the starting lineup Sunday when the Dolphins travel to New York to play the Jets.

Allen sustained the injury with 7:28 remaining in the third quarter on the same play that linebacker Jason Taylor forced Saints quarterback Drew Brees to fumble the ball on his own 15-yard line.

Initially, Allen was slow to get up, but he managed to jog off the field.

Soon after, Allen walked on his own to the locker room for further evaluation. By the end of the game, though, Allen had his leg in a large brace.

``I thought Will was playing pretty well at the time,'' Dolphins coach Tony Sparano said after the game.

Last season, Allen also dealt with knee issues, but he was able to play through a strained MCL. This injury, though, will not be one he is capable of playing with.

The transition to two rookie starters won't be an easy one, but both players have at least showed early promise. Davis and Sean Smith have made strides this season, with each one looking less and less like a rookie as they get used to NFL speed.

But without the veteran leadership of Allen to help them on the field during games, their growing pains might become more blatant. Allen was easily the team's most experienced player at the position, and he has served as a mentor to Davis and Smith.

Davis was Miami's first-round pick (25th overall) in the 2009 draft, and Smith was the team's second choice of the second round (61st overall). As a backup, Davis played a critical role in the Dolphins' first victory of the season, returning his first career interception for a 23-yard touchdown.

The rookie also was solid on special teams Sunday. But if he's now a starter, it could be difficult for the team to use him there, creating one more obstacle for the Dolphins to overcome as they search for a replacement in that special-teams role.

Since drafting the pair of cornerbacks, it was believed they would be the future of the team's secondary. That future, for now, is here -- but Allen could still return to the starting lineup next season.

Last offseason, Allen signed a two-year extension that could keep him in Miami through 2011. He was set to earn $16.2 million from this season until the end of the length of his contract, with $10 million in guarantees.