The AFC East champions have spent this week practising with the Philadelphia Eagles ahead of their game against Chip Kelly's team this evening.
The rookie wide receiver told the team's website: "Definitely jitters a little bit, just because it's something new. I'm ready for it. I'm excited to play [today].
"I feel like we got a lot done in these three days. I feel like we're taking steps forward as a team, and that's the goal."
Mankins, who has played for the Patriots since 2005, added: "It's always a big deal, getting that first one out of the way, getting your game day routine down again, get those first-game jitters out of the way. That's always a good feeling."
The Patriots will open the regular season against the Buffalo Bills.