Arhip helped to set-up the vital try for Eli Walker in the 27-26 win over the Scarlets on Boxing Day and steps down to the bench as head coach Steve Tandy fields an all Welsh international front row of Nicky Smith, Scott Bladwin and Aaron Jarvis.
Only Lloyd Ashley in the home pack is not a full international and back row man Dan Lydiate will be playing one of his former clubs. BBC Wales Sports Personality of the Year for 2015, Dan Biggar, joins Arhip among the replacements as Sam Davies gets a start at No 10.
Dragons director of rugby Lyn Jones has made five changes to the side that lost to Cardiff Blues for their New Year’s Day trip to Swansea to face the Ospreys.
Scrum half Sarel Pretorius and prop Boris Stankovich, who sat out the Blues match because of injury, both return to the starting XV.
Ospreys: Dan Evans; Jeff Hassler, Ben John, Josh Matavesi, Hanno Dirksen; Sam Davies, Tom Habberfield; Nicky Smith, Scott Baldwin, Aaron Jarvis, Lloyd Ashley, Alun Wyn Jones (captain), Dan Lydiate, Justin Tipuric, Dan Baker
Replacements: Sam Parry, Ryan Bevington, Dmitri Arhip, Rory Thornton, James King, Martin Roberts, Dan Biggar, Jonathan Spratt
Newport Gwent Dragons: Carl Meyer, Nick Scott, Adam Hughes, Adam Warren, Ashton Hewitt, Dorian Jones, Sarel Pretorius; Boris Stankovich, Thomas Rhys Thomas (captain), Lloyd Fairbrother, Matthew Screech, Rynard Landman, Nick Crosswell, Ollie Griffiths, Ed Jackson
Replacements: Elliot Dee, Phil Price, Brok Harris, Cory Hill, Nic Cudd, Charlie Davies, Jason Tovey, Ross Wardle
