OXNARD, Calif. -- Dallas Cowboys defensive tackle Henry Melton left practice with a groin strain that could keep him out for a few days, according to owner and general manager Jerry Jones.

With Melton out, rookie Ken Bishop took over as the starter at the three technique.

“We’ll have to take a little bit of a look at it,” Jones said.

Defensive lineman Tyrone Crawford left practice early with a sore calf but it is not related to the torn Achilles that caused him to miss last season.

Earlier in the day coach Jason Garrett said Melton was “still a work in progress,” in his recovery from a torn anterior cruciate ligament. Melton did not play in the preseason opener against the San Diego Chargers, like several regulars, and he said after the game he has had no issues with his knee.

While he has not missed a day of practice, he has had his work monitored. Melton played his best football under defensive coordinator Rod Marinelli with the Chicago Bears.

“You can watch the tape and see ‘Does this guy look like this guy?’” Garrett said “And like all guys coming off injuries they are probably not quite themselves. He needs a little more time and that’s the nature of this injury. The more time away from this surgery the better the guy gets if he works at it and he is certainly working hard at it.”

But Garett was not sounding the alarms.

“He is taking no backward steps,” Garrett said. “And we feel like the more we go here he is going to get more work both in practice and hopefully in these preseason games.”

That might not be the case now with the groin strain. The Cowboys will practice on Tuesday and Wednesday against the Oakland Raiders and will play the Baltimore Ravens on Aug. 16.