Other ties include relegated Hull KR’s trip to the team who replaced them in Super League Leigh Centurions and a Heavy Woollen derby between Dewsbury Rams and Batley Bulldogs.
Featherstone Rovers will be at home to Championship rivals Oldham, Huddersfield Giants play host to Swinton Lions, of the Championship and York City Knights face Barrow Raiders in an all-League One tie at Bootham Crescent.
Halifax will travel to the winners of the delayed fourth round tie between Whitehaven and Oxford.
Rhinos - the 2014 and 2015 Cup winners - and Huddersfield, along with Salford Red Devils and Leigh, enter the competition a round earlier than the rest of the Super League clubs, having featured in the middle-eights Qualifiers last year.
Rhinos’ opponents Doncaster are coached by former Batley Bulldogs boss Gary Thornton and have won their opening two League One fixtures.
Their squad includes ex-Leeds prop Jamie Thackray and former Wigan and Hull forward Iafeta Paleaaesina.
A mainly under-19s Rhinos side were beaten 35-34 at Doncaster in a pre-season game.
The full draw is: Leigh Centurions v Hull KR, Featherstone Rovers v Oldham, Leeds Rhinos v Doncaster, Salford Red Devils v Toronto, Whitehaven/Oxford v Halifax, Dewsbury Rams v Batley Bulldogs, Huddersfield Giants v Swinton Lions, York City Knights v Barrow Raiders.
Fifth round ties will be played on the weekend beginning Friday, April 21.