NEW YORK — The Yankees activated reliever Luke Weaver from the injured list Friday, sooner than initially anticipated, to bolster the back end of their bullpen.

Weaver strained his hamstring while stretching in the bullpen on June 1. He was placed on the injured list two days later and was expected to miss four-to-six weeks. Weaver beat that projection, returning in less than three weeks.

The right-hander threw a live bullpen session on Tuesday, simulating 1⅓ innings in full uniform at Yankee Stadium. It was the final checkpoint in his quicker-than-expected recovery. Afterward, Weaver said the discomfort in his hamstring subsided within a couple of days of suffering the injury.

Weaver, 30, has been one of the top relievers in the majors this season, posting a 1.05 ERA and 0.70 WHIP in 24 appearances. He began the season as the primary setup man for Devin Williams, but he was moved into the closer role in late April after Williams’ early struggles.

Manager Aaron Boone said on Friday that Weaver will be the team’s closer on “some nights” and Williams will continue to get opportunities.

Williams has since rebounded; the two-time All-Star has allowed three runs in 15 ⅔ innings (1.72 ERA) across 17 outings since May 7. This week, manager Aaron Boone said he had not yet decided whether Williams would continue as the closer or Weaver would assume the role again.