Two people with knowledge of the diagnosis said Sunday that Martin has no structural damage in his hyperextended left knee and should be ready for the opener.
Martin was injured in the second quarter of the Cowboys' 21-13 exhibition loss to Cincinnati on Saturday night. The people told The Associated Press that an MRI confirmed the Cowboys' belief that the injury wasn't serious. They spoke on condition of anonymity because there was no official update on Martin's status.
The Cowboys open the season Sept. 9 at Carolina.
Martin signed a six-year, $84 million extension with $40 million guaranteed during the offseason. The 27-year-old has made the Pro Bowl all four seasons in Dallas and started all 67 games, including three playoff games.
The former Notre Dame standout was injured when he moved into the open field and bent down to block Bengals cornerback Dre Kirkpatrick on a run by Rod Smith. With Martin in the medical tent, the Cowboys finished their only touchdown drive with Dak Prescott's scrambling 6-yard throw to Terrance Williams
''I was scared,'' Prescott said after the game. ''I was just trying to get that touchdown and go check on him.''
Martin was a first-round draft pick in 2014 and became the club's first rookie All-Pro selection in 35 years while helping the Cowboys win the NFC East and just their second playoff since the last of the franchise's five Super Bowls during the 1995 season.
The Cowboys had another injury scare with the offensive line earlier in training camp when center Travis Frederick saw a specialist in Los Angeles after a series of stingers. Frederick said he was cleared by doctors, although he likely will join Martin on the sideline for the rest of the preseason.
While Martin was getting evaluated, Frederick and fellow offensive linemen La'el Collins and Tyron Smith waited just outside the medical tent along with 2016 NFL rushing leader Ezekiel Elliott.
''It was hard in that moment to think of all the possibilities of what could be going on right then with such a great player and such a great guy who's put in so much work to make sure his game is exactly where it is,'' Prescott said. ''To see that wasn't good and it wasn't fun.''
Smith, another first-round pick and a five-time Pro Bowl selection, has been battling back issues in recent seasons. Smith, Frederick and Martin have all made the Pro Bowl each of the past four seasons.
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