Diaz will be activated from the paternity list ahead of Friday's game against the Phillies, Tim Healey of Newsday reports.
Diaz had been on the paternity list since Wednesday due to the birth of his son, but he arrived at Citizens Bank Park in time to join the bullpen for Friday's contest. The right-hander earned a win and four saves across his last five appearances prior to his absence, allowing two hits and two walks while striking out nine in five innings during that time.