The Lions square up to the Springboks in Cape Town this weekend.
And Saints fly-half Biggar said: “I think everyone who plays against South Africa knows what they’re going to present.
“Unless you match it, you’re in a bit of trouble. You’re going to get overrun.
“First and foremost it’s about making sure you play in the right areas and taking your chances.
“We’ll have some plays up our sleeves to target some areas which we see as weaknesses.
"But ultimately, when you play this team, you know you’ve got to bar up physically otherwise everything you’ve planned goes out the window.
“That’s been the big message since we got together on day one.
"They want you to make errors in your own half to allow them to have territory and get into their power game.
"It’s about staying in the arm wrestle, not giving them anything cheap and then taking your chances when you get them.”
Courtney Lawes is also looking forward to locking horns with South Africa, having impressed on the tour so far.
The Saints forward said: "We have to be ready to put our bodies on the line and we will be fully prepared to do that.
“They are going to want to dominate us up front and we have known that the entire tour.
"We saw a glimpse of it against South Africa ‘A’ and we need to be prepared for that.
"I am excited for the challenge - they play a type of rugby I enjoy playing and I am looking forward, hopefully, to getting out there and showing what I can do.”