Partnering Biggar at half back will be Luke Evans, the scrum half who joined the Blues Academy at the start of the season from Queensland Academy.
Daniel Evans, who has already played regional rugby for the Scarlets this season, is named at fullback with Principality Premiership Player of the Month for December, Leigh Halfpenny, starting on the right wing. Luke Ford, son of former Wales wing Steve, partners the Scarlets' Rhys Williams in the centre and Jimmy Norris, veteran of two IRB U19 World Championships, starts on the left wing.
Up front, Ryan Bevington, Patrick Palmer, Jevon Groves, Haydn Pugh and Nic Cudd all helped Wales reach the semi-final of the IRB U19 World Championship in Belfast last April, while hooker Ryan Prosser joins the squad from Bristol Academy and back rowers Justin Tipuric and Rory Pitman were both teammates of Daniel Biggar in last season's Wales U18 squad. Groves captains the side.
Wales U20 Head Coach Patrick Horgan said, "The side the Ospreys have picked for this game is very close to the side that played against Leinster in the Magners League last weekend.
"We are delighted about that because we asked the Ospreys for some quality opposition in order to prepare the boys for the tough international season ahead which includes the Six Nations Championship and the inaugural Junior World Championship here in Wales.
"Playing against a team of full-time professionals will stand our players in good stead for the quality sides they will face in the coming weeks and months.
"There are four or five players ruled out through injury, while Jon Davies is involved in the Scarlets' Heineken Cup action this weekend. All the other squad members will get some game time and we are looking forward to seeing how players react to a match situation."
Wales U20 v Ospreys XV
Monday 14 January, kick-off 7.15pm, Aberavon RFC
Wales U20: Daniel Evans (Scarlets); Leigh Halfpenny (Blues), Luke Ford (Blues), Rhys Williams (Scarlets), Jimmy Norris (Dragons); Daniel Biggar (Ospreys), Luke Evans (Blues); Ryan Bevington (Ospreys), Ryan Prosser (Bristol), Patrick Palmer (Blues), Jevon Groves (Blues), Haydn Pugh (Scarlets), Justin Tipuric (Ospreys), Nic Cudd (Scarlets), Rory Pitman (Ospreys)
Replacements: Sam Hobbs (Blues), Scott Andrews (Blues), Rhys Lawrence (Ospreys), Ben Roberts (Dragons), Ashley Sweet (Dragons), Lloyd Phillips (Scarlets), Gareth Williams (Ospreys), Jason Tovey (Dragons), Gareth Owen (Ospreys), Nathan Rees (Blues)
Ospreys: Jonathan Vaughton; Kristian Phillips, David Bishop, Jonathan Spratt, Aled Brew; Shaun Connor (Capt), Martin Roberts; Craig Mitchell, Ed Shervington, Cai Griffiths, Andrew Lloyd, Lyndon Bateman, Hale T-Pole, Ben Lewis, Tom Smith
Replacements (selected from): Mark Breeze, Andrew Millward, Michael Collins, Mike Powell, Steve Tandy, Sam Kylie, Rhodri Wells, Adrian Thomas, David Evans, Ryan Bayliss