Youngs started the 38-18 Six Nations win over Scotland at the weekend, with Hartley coming on for the final 35 minutes. However, the former is once more expected to be given a starting role against Ireland on Saturday.
"For me at the moment it's all about opportunities. I was injured and out for five weeks and Tom's come in and done a good job, but it's about coming on and playing well when I get my chance and putting a bit of pressure on him," he told Sky Sports News.
"Like any team, competition is healthy. If you look at myself and Tom, I think I'm getting the best out of Tom by pushing him at the moment and in the centre partnership it's the same thing there. It's important and it's healthy, you get the best out of people that way."
Ireland opened their campaign with a 30-22 win over Wales.