The Giants lost the services of one of their starting receivers and top players on Thursday, as Sterling Shepard suffered a fractured thumb in the first practice of training camp. He will be out of action for at least two weeks then evaluated on a week-to-week basis.

The Giants open their regular season Sept. 8 against the Cowboys. Given this injury and the precaution the Giants will take with one of their most important players, Shepard is likely to miss most of, if not all of the preseason.

Shepard was injured when he reached down attempting to scoop up a low pass from Eli Manning, with cornerback Janoris Jenkins defending on the play. Shepard made the catch but came away holding his left hand. He was forced out of the remainder of practice, and X-rays revealed the fracture.

This is a big blow to the Giants. Shepard, 25, was poised to emerge as a team leader and a key member of an offense that sent superstar receiver Odell Beckham Jr. to the Browns. Shepard signed a four-year extension worth $41 million this offseason, keeping him contractually bound to the Giants through the 2023 season. He is one of the players the Giants want to build around, and now he will be unavailable for much of the summer.

With Beckham gone, the Giants are counting on Shepard to emerge as a No. 1 receiver.

“Sure, I think he can be,” coach Pat Shurmur said. “Sterling is a football player, and we appreciate his toughness and his ability to make plays, and all the things he adds to the team. He’s a value-added guy in my mind. He plays his position, but he makes the people around him better. I think that’s what all the players should strive to do.”

After Shepard went out, the Giants used Golden Tate, Cody Latimer and Corey Coleman as their receivers with the first-team offense. Tate, 30, was signed the day after the Beckham deal became official and, for now, is the only proven receiver for Manning to target.

Shepard started all 16 games last season and had 66 receptions for 872 yards and four touchdowns.