TAMPA, Fla. (AP) -- Chris Simms went to the ground on one knee and leaned over clutching his midsection.
The battered Tampa Bay Buccaneers quarterback later had his spleen removed Sunday night and is out indefinitely after absorbing several punishing hits during a 26-24 loss to the Carolina Panthers.
"Chris is doing well and we anticipate a full recovery," team physician Dr. Joe Diaco said in a brief statement, adding the 26-year-old son of former New York Giants quarterback Phil Simms was in stable condition following surgery.
It was not clear if Simms was hurt on a particular play or if the injury resulted from an accumulation of blows.
The fourth-year pro left briefly but returned to lead a fourth-quarter field goal drive that gave Tampa Bay a 24-23 lead with five minutes remaining. He finished the game, accompanying teammates to the locker room on his own power.
The Bucs did not immediately announce that Simms was taken to St. Joseph's Hospital, a few blocks from Raymond James Stadium. Team officials simply said he would not be available for postgame interviews because he was with doctors and trainers.
Coach Jon Gruden, meanwhile, said Simms hurt his ribs early in the game and was also battling dehydration.
"He is hurting right now, there is no question," Gruden said. "He left the game. I don't know that it was because of his ribs, dehydration or both."
Simms was replaced by rookie Bruce Gradkowski for the last play of the third quarter and first play of the fourth.
Although the Bucs said Simms went to the locker room because he was cramping, the quarterback didn't appear to be the same after being hit at the goal line on a 2-yard TD run that gave Tampa Bay a 21-20 lead with just under six minutes left in the third.
The Bucs did not speculate on how long Simms might be sidelined. The recuperation time for a normal person is four to six weeks, though it's unclear how long it might take to heal enough to play football.
Simms had a blood transfusion as part of his treatment and was expected to be hospitalized for several days, Peter King said during a break on NBC's Sunday Night Football, citing a conversation the Sports Illustrated reporter had with Simms' mother, Diana Simms.
The spleen is an organ located in the upper left side of the abdomen, storing blood and breaking down old blood cells to help the body fight infections. Many people live productive, healthy lives without it.
The loss of Simms is certainly a blow to a Tampa Bay team looking to recover from an 0-3 start.
He completed 13 of 24 passes for 139 yards, one touchdown and one interception Sunday. The Panthers sacked him once and linebacker Adam Seward hit him hard when Simms faked a handoff to Mike Alstott and ran around left end on fourth-and-1 to score his TD.
The Bucs have a bye next week, giving Gruden extra time to sort out the quarterback situation and possibly bring in a veteran.
Gradkowski, a sixth-round draft pick from Toledo, earned the backup job over third-stringer Tim Rattay in training camp.
Simms was a third-round draft pick in 2003. He took over the No. 1 job last season when Brian Griese was lost for the year in the sixth game and helped the Bucs finish 11-5, win the NFC South and make the playoffs for the first time since their 2002 Super Bowl run.
He has struggled this year, though, playing poorly in a 27-0 season-opening loss to Baltimore and following that up with an equally disappointing performance in a 14-3 loss at Atlanta.
His first pass Sunday was intercepted, setting up Carolina's first touchdown. He settled down to lead an 82-yard TD drive in the second quarter and took advantage of three turnovers to overcome a 17-0 deficit and nearly beat the Panthers.
In 15 career regular-season starts, Simms is 7-8. He also lost his only playoff start last year.