Romo ruled out for the rest of NFL season

Dallas Cowboys veteran quarterback Tony Romo will miss the rest of the NFL season after re-injuring his collarbone, the team confirmed on Friday.

Cowboys owner Jerry Jones told Dallas radio station 105.3 The Fan that Romo suffered a hairline fracture when he fell hard on his left shoulder after being sacked at the end of the third quarter of Thursday's loss to the Carolina Panthers.

Romo, who was playing in his second game back from a broken collarbone that forced him to miss seven games, will not have surgery for the injury, according to Jones.

Losing Romo is a massive blow to the Cowboys' fading playoff hopes. Dallas lost all seven games that Romo missed earlier this season due to a broken left clavicle.

He returned last week in a 24-14 win over the Miami Dolphins and Dallas were hoping Romo would provide a jolt to start a playoff run.

Romo laid on the field for several minutes following the hit before walking off as he favoured his left arm. After the game Romo said the injury felt "similar" to what he felt when he broke his collarbone earlier this season.

Prior to the injury, Romo was struggling through Thursday's game, completing only 11 of 21 passes for 106 yards while two of his three interceptions were returned for touchdowns in the first half.

The Cowboys, who Forbes ranked as the world's most valuable sports franchise in September with a value of $US4 billion, are last in the four-team NFC East division with a 3-8 record and five regular season games remaining. Their next game is December 7 at Washington.

Matt Cassel replaced Romo in the fourth quarter, completing 13 of 19 passes for 93 yards and a late touchdown, and is in line to assume the starting role versus the Redskins.