Chris, who replaces Mike Blair at scrum-half, said: "I didn't see it coming. That said, I was really pleased with my impact off the bench in the last two games, but I am still delighted.
"I am confident, I am playing well and it is nice to get a start in the last game of the season."
It was a similar story for Lamont, who seems to make a habit of getting into the side when Samoa are around.
"I had presumed he (Andy Robinson) would go with the same team as he did last week, with me on the bench," he admitted.
"I am grateful that I have an early chance. I still love playing for Scotland so any chance to go on the field is good.
"My first cap was against them, so was my 50th. Outside the Six Nations, the only team I have played more often than Samoa is Australia."
Sean - who re-joins Glasgow for the new season - is relishing the confrontation with the confidence of being familiar with the majority of the Samoan side from club clashes in European competitions.
"Obviously I have played against a few of them but I have not seen their team yet so I'm not exactly sure who will be there," he said. "Quite a few of the boys across the board are players we know from having played with them or against them, they are excellent players.
"We know a lot of their players from European rugby and in general they are simply a more structured team than the Fiji side we faced last week, whether that is a result of the time they have had together or the players they have got. They will be a big threat, especially on home soil."
For the Glasgow scrum-half, one reason he is there is to mark the Samoan dangerman Kahn Fotuali'I out of the game.
The rival scrum-halves know each other well from club meetings in the RaboDirect Pro12 - Fotuali'i plays for the Ospreys and Chris said: "Kahn Fotuali'i is a cracking player.
"He has had a good year at the Ospreys, he played very well in their game against Japan the other day and is a key player for them.
"They have a lot of guys back in the side who play in Europe and we know them a lot better than we did the Fijians last week, so it is going to be a different challenge.
"I think the chance to come over here is unique and it brings its own challenges, just with the heat and the weather conditions, as well as the quality of players they have got."
Scotland
15 Stuart Hogg (Glasgow Warriors)
14 Sean Lamont (Glasgow Warriors)
13 Nick De Luca (Edinburgh Rugby)
12 Matt Scott (Edinburgh Rugby)
11 Tim Visser (Edinburgh Rugby)
10 Greig Laidlaw (Edinburgh Rugby)
9 Chris Cusiter (Glasgow Warriors)
1 Ryan Grant (Glasgow Warriors)
2 Ross Ford (Edinburgh Rugby) CAPTAIN
3 Euan Murray (Newcastle Falcons)
4 Richie Gray (Sale Sharks)
5 Alastair Kellock (Glasgow Warriors)
6 Alasdair Strokosch (Perpignan)
7 Ross Rennie (Edinburgh Rugby)
8 Richie Vernon (Sale Sharks)
Substitutes to be confirmed later this week