Leinster's Nathan Hines moves from the blindside flank to lock, with Kelly Brown taking over from Hines having begun the historic win over South Africa at No8.
On the bench, Scotland welcome back Edinburgh scrum-half Mike Blair, who replaces his Magners League clubmate Greig Laidlaw after recovering from the knock to the head he suffered against New Zealand.
Glasgow centre Max Evans has also recovered from a shoulder injury he sustained in that game and will take over from Chris Paterson among the replacements.
"I thought Richie Vernon showed his mettle as an international rugby player when he came on for Scott MacLeod last Saturday and he has a chance to demonstrate those traits from the start on Saturday," said Scotland head coach Andy Robinson.
"Our supporters were understandably delighted by our win against South Africa but that game is now history and we have to start afresh against quality international opposition in Samoa.
"They will bring their own very physical, hard-running dimension to Saturday's game and we need to be absolutely focused on upping our performance this weekend."
Scotland came back from a disappointing defeat to the All Blacks in their opening game of the autumn series to produce a sensational display against the world champion Springboks at Murrayfield.
Dan Parks kicked all 21 points in a famous victory that saw Scotland rise to sixth place in the IRB World Rankings, five places above Saturday's opponents Samoa.
They will now look to consolidate their position as the highest ranked Celtic nation with a fifth win in six games since the 15-15 draw with England in early March.
Saturday's match at Pittodrie Stadium in Aberdeen will be a landmark occasion for two Magners League players as Edinburgh's Allan Jacobsen and Sean Lamont of the Scarlets reach 50 international caps.
Prop Jacobsen and wing Lamont are both in the starting line up to face the Samoans, with Jacobsen reaching a half century eight years after making his Scotland debut in 2002 and Lamont getting there two years quicker having joined the international ranks in 2004.
"I also want to congratulate Chunk (Jacobsen) and Sean Lamont as this weekend will mark their 50th caps. Both have had periods of injury adversity in their careers but they have shown the sort of determination we will need on Saturday to return from such experiences to be better players for it," added Robinson.
Scotland (vs Samoa)
H Southwell (Stade Francais); N Walker (Ospreys), J Ansbro (Northampton), G Morrison (Glasgow Warriors), S Lamont (Scarlets); D Parks (Cardiff Blues), R Lawson (Gloucester); A Jacobsen (Edinburgh), R Ford (Edinburgh), E Murray (Northampton), N Hines (Leinster), R Gray (Glasgow Warriors), K Brown (Saracens), R Vernon (Glasgow Warriors), J Barclay (Glasgow Warriors)
Replacements: D Hall (Glasgow Warriors), M Low (Glasgow Warriors), J Hamilton (Gloucester), R Rennie (Edinburgh), M Blair (Edinburgh), Ruaridh Jackson (Glasgow Warriors), M Evans (Glasgow Warriors)
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