England skipper Chris Robshaw feels Argentina will provide stern opposition in Saturday's Test at Twickenham.
Robshaw's side got their November Test campaign off to a fine start with a 20-13 victory over Australia last weekend and they will be keen to build on that performance against the Pumas.
Robshaw feels Argentina have changed their outlook on the game since competing against Australia, New Zealand and South Africa in the Rugby Championship earlier this year.
"There are a lot of differences," he said.
"Argentina are traditionally known for their strong scrum, physical forwards, physical back, but I think you've seen in the last two years how much they've developed going into the Championship.
"They've got a much more free flowing game, they tested the kind of three or four best teams in the world. It will be a massive challenge for us."
Robshaw believes building momentum is crucial to the way his side has been performing, especially with their next Test being against New Zealand on November 16.
But although he is keen not to let that wane he will also be while trying not to take the focus off the challenge Argentina will provide.
"We've started this series fantastically and we need to kick on," added Robshaw.
"We got some huge momentum, beating Australia for the first time myself. We know now what it takes to beat one of the southern hemisphere sides.
"I think whenever you go into a series you want to get off to a win first and foremost then you build on the performance. Of course you always want a perfect performance but you'd rather take a win I think.
"As pro players and athletes you focus on the next game. As soon as you take a team like Argentina lightly then you're in a world of trouble.
"You need to make sure you're professional in everything you do, keep improving as a team and make sure you get the right result."