The Giants took the rare route of using a supplemental draft pick last week, selecting cornerback Sam Beal in the third round. Now it looks as if that plan has gone awry, at least for this season.

Beal has a history of shoulder issues and aggravated a shoulder injury Monday during practice with the Giants rookies and select veterans in a pre-training camp session.

A variety of treatment options have been discussed, including protecting the shoulder in a harness while Beal attempts to stay on the field. Another option is surgery, which would end his rookie season before it starts. The likely outcome is that Beal will have the surgery and miss the entire season.

Oddly, after aggravating his shoulder on Monday, Beal participated in Wednesday’s practice inside the field house. After that practice, coach Pat Shurmur described Beal as a “very, very talented guy, his movement skills are tremendous,’’ and added, “We feel he can compete to make our team.’’

Beal, 6-foot-1 and a skinny 177 pounds, was a two-year starter at Western Michigan and while in college had an interception off USC’s Sam Darnold. Beal did not figure prominently in the defensive puzzle this season and was considered more of a project with potential down the road.

“We’re constantly looking to upgrade at all the positions and felt like he’d be a great player to add to our team,’’ Shurmur said Wednesday.

With the selection of Beal, the Giants forfeit a third-round pick in the 2019 draft.

“We feel like we’re getting our third-round pick now,” general manager Dave Gettleman said in a statement after the Giants took Beal. “We just feel it gives us a really talented young kid with the ability to ascend.”

It appears as if that ascension will have to wait.