MEMPHIS, Tenn. In the relative world of golf, Jordan Spieths opening 63 at the FedEx St. Jude Championship was tied for his best round of the year but it didnt feel like it. 

Spieth didnt have a bogey on Day 1 at TPC Southwind. He chipped in for eagle at the par-5 16th hole and was second in the field in strokes gained: tee to green and eighth in strokes gained: putting. 

But the best this year? Apparently not.

I was telling [caddie Michael Greller] maybe sometime on the back nine, I was like, I feel good, but it doesn't quite feel as tight as some of the days in the last week or so ball-striking, Spieth said. Then all of a sudden I ended up hitting a good one on 15 and then chipping in on 16, now it's three strokes better, so it's like, how can you not. Yeah, I think it was solid.

Spieths solid round left him alone atop the 70-man field at the playoff opener and on pace to win his first event of the season. But despite his flawless start, he explained theres still plenty of room for improvement.

I used the heel of the driver a lot today, and I don't want to keep doing it, Spieth smiled. I've been driving the ball really, really nicely and everything kind of goes from there. If I feel really confident stepping into a driver, getting in front of some shots and hitting some nice ones, that normally feeds to the rest of the bag, so I'd like to improve. But I hit some pretty far off the heel and then I toed one on 17.

This is Spieths first start since last months Open Championship, and during that break, he said he forced himself to practice less and play more while he was at home in Dallas.

I did that [play instead of practice] a ton in the spring, and then my wrist [injury], I was trying to rest, Spieth said. I just found that I wasn't playing a ton in that break between U.S. Open and Scottish Open, and so I just got to the Scottish, and I felt like things were good, but I just wasn't scoring, so it was pretty frustrating.

Some of that just has to do with knocking putts in, and some of it has to do with actually getting out there and not just being on a driving range or a putting green.