Per ESPN's Ed Werder, Cooper is "doing well and making progress" after suffering the injury 10 days ago.
Cowboys head coach Jason Garrett said Cooper is "getting closer to returning" but the "team doesn't want to rush him back" from a bruised heel to avoid making it worse, per Rob Phillips of the team's official website.
The Cowboys turned heads when they acquired Cooper from the Oakland Raiders in October. While many expected Dallas to add a receiver before the trade deadline, sending a 2019 first-round draft pick looked like an overpay.
Prior to the trade, Cooper had 22 receptions for 280 yards and a touchdown, and his 12.7 yards per catch were more than a full yard below his career low (13.9) over a full season.
He made an immediate impact for his new team, catching five receptions for 58 yards and a touchdown, albeit in a losing effort to the Tennessee Titans.
Cooper's Thanksgiving Day performance (eight catches for 180 yards and two touchdowns) endeared him further to fans, and he had a 10-catch, 217-yard, three-touchdown outing in a 29-23 overtime win vs. the Philadelphia Eagles two weeks later.
Cooper caught 53 passes for 725 yards and six touchdowns for Dallas overall.
If Cooper is out for any stretch of time when the regular season starts, Cobb will have to take on a large role in Dallas' passing game.