Boss Chris Boyd had named a 33-man squad for the encounter, which comes nine days before the season starts with a Premiership Rugby Cup trip to Sale Sharks.
Centre Rory Hutchinson will start after his shock omission from Scotland's World Cup squad.
Alex Waller will captain the team, with Tom Wood providing plenty of wisdom from the back row.
Scrum-half James Mitchell, who has signed on a short-term deal, is given the No.9 shirt, while summer signing Ryan Olowofela starts on the wing.
There will be more new players among the replacements, with hooker Michael van Vuuren and scrum-half Henry Taylor also hoping to get some game time.
But Saints do have several injuries to contend with, as Alex Mitchell (knee) and Reece Marshall (hamstring) are among the names on the list of casualties.
Dylan Hartley continues to work his way back from a knee problem, with Harry Mallinder, Mike Haywood and Andy Symons still getting up to speed following ACL injuries.
Jamie Gibson misses out with a shoulder injury, while George Furbank has been in training but is not selected as he continues to get back from the concussion he sustained against Harlequins in April.
Young prop Toby Trinder also misses out as he has a back injury.
Meanwhile, Ross Molony will captain Leinster, who are gearing up for their September 28 Guinness Pro14 season opener at Benetton.
Caelan Doris lines up at No.8 with Max Deegan and Scott Penny, involved for the first time since his shoulder operation, flanking him in the back row.
Hugh O’Sullivan and Ciarán Frawley are the half-back duo while Joe Tomane and Jimmy O’Brien will play outside them in midfield.
Hugo Keenan slots in at full-back with Cian Kelleher and Fergus McFadden on the wings.
Jamison Gibson-Park could be set to make his return to action after picking up an injury against Glasgow Warriors towards the end of last season.
Head coach Leo Cullen has named an extended bench of 13 players for the trip to the Gardens.
Saints: Tom Collins; Ollie Sleightholme, Rory Hutchinson, Fraser Strachan, Ryan Olowofela; James Grayson, James Mitchell; Alex Waller (c), James Fish, Paul Hill; Devante Onojaife, David Ribbans; Tom Wood, Ollie Newman, Mitch Eadie.
Replacements: Michael Van Vuuren, Will Davis, Ben Franks , Karl Garside, Ehren Painter. Lewis Bean, Alex Coles, Teimana Harrison, JJ Tonks, Tui Uru, Henry Taylor, Connor Tupai, Tommy Mathews, Reuben Bird-Tulloch, Fraser Dingwall, Tommy Freeman, Josh Gillespie, Taqele Naiyaravoro.
Leinster: Hugo Keenan; Fergus McFadden, Jimmy O’Brien, Joe Tomane, Cian Kelleher; Ciarán Frawley, Hugh O’Sullivan; Peter Dooley, Rónan Kelleher, Michael Bent; Ross Molony (c), Ryan Baird; Max Deegan, Scott Penny, Caelan Doris.
Replacements from: Bryan Byrne, James Tracy, Michael Milne, Roman Salanoa, Scott Fardy, Josh Murphy, Will Connors, Jamison Gibson-Park, Ross Byrne, Dave Kearney, Conor O’Brien, Rory O’Loughlin, Adam Byrne.