The 33-year-old Spaniard shot four birdies on the front nine, before adding another at the 10th to go five-under par.
He went on to grab a share of the lead by picking up another shot at 15, before going completing a bogey-free round of 66.
"What I'm going to try to take to my pillow tonight is the first 10 holes," Garcia told reporters.
"Without a doubt, it's the best 10 holes I've ever played at The Masters."
"I felt so good. I hit so many good shots. It felt like I was 10 or 15 feet away all the time, and that's hard to do on this golf course."