Wayne Pivac’s shared the spoils with the South Americans in their first meeting at Cardiff’s Principality Stadium after coming back from a 14-point deficit.
Argentina lost Juan Cruz Mallia to a first-half red card for tackling Kieran Hardy high, but they led 20-6 at one stage in the second half before Wales turned the tables.
“There was a large period of the game with them down a man. It was tough and we weren’t as clinical as we should have been,” said Amos, who impressed at full-back.
“We lost a couple of balls deep in their 22 which was a bit frustrating. It was the first time a lot of us had played together, especially in the backs.
“Obviously Jonathan Davies has got a lot of caps, but beyond that there are not many boys with all that much experience so I thought we acquitted ourselves pretty well.
“Hopefully we can go one better next week. Wayne said after the game that the series will rest on this last game which is quite a nice place to be and hopefully we can finish the season on a high.”
Amos was also pleased to get a run out in his favoured position of full-back.
“It’s where I prefer to be,” he added.
“It’s a position where I see myself moving forwards and I’ve gone alright there for Cardiff Rugby as we now are.
“It was sad to see Leigh Halfpenny go down with an injury against Canada, but hopefully I’ve done his shirt proud.”
Argentina scored tries in either half through Pablo Matera and Jeronimo de la Fuente after Callum Sheedy had kicked two Welsh penalties.
It left Wales up against it but replacement scrum-half Tomos Williams made a big impact in the second half by creating a try for Will Rowlands and scoring one himself.
“He was great today. He’s a fantastic player,” Amos said of Williams.
“He’s one of my best mates in the squad. We are blessed in Wales to have four or five outstanding nines.
“We’ve got Gareth Davies who is away with the British & Irish Lions, but the three boys who are here are all fantastic and are starting international games.
“Tomos was fantastic when he came on and he always is. It’s great to have someone with that speed of thought.
“I don’t think there are many boys who are as skilful as him. When he’s carrying the ball one handed like Alun Wyn Jones and he’s only five foot four it’s pretty impressive.”
Amos is now looking forward to the series decider next week.
“It’s a great opportunity for us. Argentina are a fantastic side and we know now what they are going to bring,” said Amos.
“I don’t think we’ve played them since 2018 so sometimes it’s hard to see what a team is going to bring, but now we know.
“Hopefully it’ll be an even better game next week.”
