Lahiri, who finished second in a spectacular Players Championship final three weeks ago, finished 1 of 10 holes at TPC San Antonio before heading home with five birdies, thanks in large part to a hot putter.
Scotsman Russell Knox opened with a 65 to lead the $8.6 million PGA Tour event.
Lahiri, 34, is bidding for a first career title in the United States after coming awfully close to the Tour’s showpiece tournament at TPC Sawgrass, and Sunday’s win would also secure him a spot in next week’s Masters tournament. .
“Today was about trying to find the same kind of rhythm in my routine, the rhythm of how I was swinging the club.
“The body still looks a bit rusty. When I started it was a bit cold and there was a bit of moisture on the surface and I was trying to get a good feel and green speed,” Lahiri said Thursday.
“I really wanted to get my groove back after being out and battling an infection I got from my daughter. I was bedridden for a few days and didn’t play much golf, but I didn’t really hit a lot of bad shots.”
Starting on the 10th, Lahiri raced through his first 10 holes with two bogeys against a single birdie before his putter began to find range.
He rolled in a nine-footer in the second, a 23-footer in the fifth, then birdied three successive nine-footers, 18-footers and 30-footers respectively to close his round in style.
“On the back nine, I found the speed of the greens. I’ve played this course quite a bit and I understand the nature of this course.
“You just try to get yourself in good positions and places where you can make aggressive swings and aggressive putts. If you can do that, you can make some birdies.
“The putter warmed up a bit and that was a nice bonus on the last one to get a long that feels really good,” said Lahiri, who finished fifth in solo at TPC San Antonio last season.
Despite his brilliant finish at Tje Players, Lahiri intends to keep his foot on the pedal in an attempt to regain his place among golf’s elite. He was ranked 33rd in the Official World Golf Rankings in 2015 and has twice appeared in the Presidents Cup for the international team.
“The Players Championship was fantastic and that’s in the past now. It’s time to move on and try to be in the present, which was pretty much what I did.
“I’m just trying to do the same, stay in the present, stay in the present, do what I need to do, what I need to feel, what I need to work on. I’m just trying to come back to that and it’s good to see my golf react,” Lahiri said.
South Korea’s Si Woo Kim and Chinese Taipei’s CT Pan got off to a strong start at the Valero Texas Open with matching 69s.
Despite missing six greens in regulation, Pan, who won the Tour once, kept bogeys off his card while Kim netted five birdies against two bogeys.
Japanese star Hideki Matsuyama, who will defend his Masters title next week, started with a 74 in his first appearance since withdrawing from the Players Championship with a back injury.