NEW ORLEANS (AP) — Deuce McAllister said an MRI Tuesday morning confirmed his worst fears as he limped off the field favoring his left knee a night earlier: he had torn his anterior cruciate ligament and would miss the rest of the season.

‘‘I didn’t want to believe, but just taking that walk to the locker room you could feel it just kind of giving way a little but, and that was just kind of reminiscent of how the other one felt,’’ McAllister said, referring to a 2005 injury.

The latest injury occurred when McAllister landed awkwardly after catching a short pass from Drew Brees in the second quarter of the Saints’ 31-14 loss to the Tennessee Titans.

McAllister said there was also some damage to his medial collateral ligament.

Five games into the 2005 season, McAllister tore his right ACL during a run in Green Bay. After reconstructive surgery, he returned to rush for 1,057 yards in 2006, helping the Saints to the NFC South Division title and starring in their playoff victory over Philadelphia.

Now, for the second time in three seasons, McAllister needs reconstructive knee surgery, to be followed by the long, painful rehabilitation that will likely last until close to the time that 2008 training camp begins.

It’s a potentially devastating blow to the Saints, who are 0-3 and in desperate need of a victory to have any hope of rallying back into postseason contention.

Meanwhile, McAllister, 28, can only hope he can come back again and regain the form that made him the Saints’ all-time leading rusher, with 5,678 yards and 44 touchdowns.

‘‘Obviously, the questions: Will you ever be the same? Will you ever be the back that you once were? Those are the different thoughts that obviously run through your mind as a player,’’ McAllister said. ‘‘We’ll see how the surgery goes and we’ll go from there.’’