Leeds Rhinos legend Kevin Linfield has returned to the club as director of rugby.
The ex-England captain, 37, will take charge of his first game on Sunday 8 July when Leeds face Castleford.
The Headingley club sacked head coach McDermott on Monday after seven successive Super League defeats and Huddersfield's win against Hull FC on Thursday sent the defending champions into the bottom four in the table.
Leeds won seven Super League titles, two Challenge Cups and three World Club Challenges with Sinfield as skipper.