"We've made the changes to the pack with a view to improving the supply and quality of possession," Johnson told the Scottish Rugby Union website (www.scottishrugby.org).
"Italy are formidable opponents, especially in Rome, and Scotland's matches against them in recent years have been a real arm wrestle."
Both sides are without a victory after two matches and determined to win in an attempt to avoid last place.
Scotland lost their first match to Ireland 28-6 in Dublin, before being held scoreless in a meek 20-0 defeat by England at Murrayfield.
"I was not involved against England but I think the guys were pretty down and they did not manage to show what they can do," Gray said.
"So I think this weekend it's really about showing what we can do."
Greig Laidlaw will remain as captain in the continued absence of flanker Kelly Brown, who was dropped for the England match.
Scotland have won the past two meetings with Italy in all competition but have not beaten them in Rome since 2006.
Team: 15-Stuart Hogg, 14-Tommy Seymour, 13-Alex Dunbar, 12-Matt Scott, 11-Sean Lamont, 10-Duncan Weir, 9-Greig Laidlaw; 8-Johnnie Beattie, 7-Chris Fusaro, 6-Ryan Wilson, 5-Jim Hamilton, 4-Richie Gray, 3-Moray Low, 2-Scott Lawson, 1-Ryan Grant
Substitutes: 16-Ross Ford, 17-Alasdair Dickinson, 18-Geoff Cross, 19-Tim Swinson, 20-David Denton, 21-Chris Cusiter, 22-Duncan Taylor, 23-Max Evans
(Reporting By Josh Reich; Editing by Rex Gowar)
