The 36-year-old, who has finished second twice in the Indian Open, picked up six birdies to share the lead with Richard Lee (Canada), Chapchai Nirat (Thailand), Siddikur Rahman and Joakim Lagergren (Sweden) at the tricky Delhi Golf Course (DGC) here.
"I played very well and was bogey free. I made some good putts and was hitting it good off the tees. It looked easy but it wasn't! My putting was good so that's the key," Chowrasia told reporters after his round.
"This is my National Open and all the Indian golfers enjoy playing in this event. I'm not thinking too much about the course, I'm just enjoying myself," said Chowrasia, who won his first European tour title after clinching the inaugural Indian Masters in February, 2008.
A 10th tee starter, Chowrasia sank birdies at the 12th, 17th and 18th holes to reach the turn in 32 before picking up further birdies at the first, sixth and eighth in a flawless round.