The Indian recovered from a bogey on the first hole to roar home in five under after the turn and six under overall, including an impressive approach at the 17th and a 15-foot putt for birdie at the last.
It helped the 42-year-old to a round of 64, which was enough to put him a shot clear of Angelo Que of the Philippines, with Belgium's Nicolas Colsaerts one of nine players tied for third.
Colsaerts was fourth at the Wales Open and Portugal Masters runner-up in recent weeks and continued his strong form by carding five birdies on the way to a four-under 66.
Having bogeyed at the third shortly after the turn, Colsaerts was in fine form on his way back with birdies at the fourth, fifth and eighth.
They included 20 and 30-feet putts at the fourth and fifth, with the Belgian satisfied with his first round.
"You need to play well to shoot any sort of score under par," he told the European Tour website.
"From tee to green you need to be pretty good to leave yourself birdie chances.
"I'm quite happy with my score."
Defending champion Miguel Angel Jimenez is in the running for a third consecutive Hong Kong Open title at the event in Fanling, but the Spaniard finished two over due to three bogeys.
Jimenez is bidding to become the first person to win the tournament on three consecutive appearances.