Two of Scotland's starting changes come in the backline where Edinburgh wing Darcy Graham and Gloucester centre Chris Harris - try scorers against Georgia and France in respective Summer Tests - start in place of Tommy Seymour and Duncan Taylor, the latter moving to the bench.
A new back-row trio makes up the three remaining changes in the pack.
Fit-again Jamie Ritchie starts in place of the injured Hamish Watson (knee), with Watson’s wider squad replacement Magnus Bradbury operating on the blindside, and Scarlets Blade Thomson at number 8.
The forwards are completed by a returning tight-five of loosehead prop Allan Dell (London Irish), hooker and captain Stuart McInally and tighthead prop Willem Nel (both Edinburgh), with Grant Gilchrist (Edinburgh) and Jonny Gray (Glasgow Warriors) back at lock.
Townsend, said: "Samoa are a team capable of scoring points from anywhere on the field. They play an ambitious brand of rugby and their team is full of skilful and powerful players.
"We had worked hard in our build-up this tournament to deliver our best rugby but we were well below this level in our opening game against Ireland. We'll need to be much better on Monday night against such a dangerous opponent."
He added: "It's been a long week building towards a game where we intend to put a lot of things right.
"The players have responded well in training, know what is required of them and are hungry to deliver the kind of performance that keeps us in the world cup.
"The reality is we now have to win our next three games to make it out of our pool, so the knockout stages for us begin this Monday night."
"I firmly believe this group are ready to take on that challenge."
15 Stuart Hogg VICE CAPTAIN (Exeter Chiefs)
1 Allan Dell (London Irish)
2 Stuart McInally CAPTAIN (Edinburgh)
3 Willem Nel (Edinburgh)
4 Grant Gilchrist (Edinburgh)
5 Jonny Gray (Glasgow Warriors)
6 Magnus Bradbury (Edinburgh)
7 Jamie Ritchie (Edinburgh)
8 Blade Thomson (Scarlets)
16 Fraser Brown (Glasgow Warriors)
17 Gordon Reid (Ayrshire Bulls)
18 Zander Fagerson (Glasgow Warriors)
19 Scott Cummings (Glasgow Warriors)
20 Ryan Wilson (Glasgow Warriors)
21 George Horne (Glasgow Warriors)
22 Adam Hastings (Glasgow Warriors)
23 Duncan Taylor (Saracens)