Lahiri, high on confidence having played two Majors and then being honoured with Arjuna Award at home, will seek to augment his lead at the top of the Asian Tour's Order of Merit.
Chowrasia shot 72 and was still at three-under for 36 holes in tied 44th place, while Shiv Kapur (69) was at two-under 142 and in tied 57th place.
Kapur's 23rd put him alongside Rory McIlroy, Aaron Baddeley and Francesco Molinari and five spots ahead of Phil Mickelson and former US Open winner, Graeme McDowell, who were both tied 28th.
Kapur, making his debut at the US Open after coming through the qualifiers, was steady for the first eight holes, with one birdie on the 13th and no bogeys.
At the top Spaniard Alvaro Quiros landed two eagles in a round of 67 to get into a three-way lead with Frenchman Victor Dubuisson and England's Eddie Pepperell at the halfway mark.
Kapur, who has played at the 2006 and 2013 British Open, was tied fifth as 14 players made it to the Major through the qualifiers held in Walton Heath Golf Club. The Sectional was won by Shane Lowry of Ireland.
India's other two challengers in the event, Jeev Milkha Singh shot 72 and Gaganjeet Bhullar carded 73. Kapur, whose first round was interrupted by bad weather yesterday, had five birdies after opening with bogeys on first and third.
Kapur was the only Indian to fall inside the cut line as Jeev Milkha Singh (75-69) and Gaganjeet Bhullar (77-74) exited early from the tournament.
The Nelson Mandela Championship is the fifth event on the 2014 European season, for which Kapur has already got a full card.
Kapur conceded he must erase the mental mistakes to overcome a six-shot deficit from leaders Stroud and Moore.
The 31-year-old Indian star is eight shots behind the leader, American Keegan Bradley at the Kuala Lumpur Golf and Country Club's West course.
Kapur birdied second, third and fourth and then added two more on 13th and 14th. His bogey came on the 17th.
Both Lahiri and Kapur were done in by finishing blues. Lahiri seemed to have fought back well after a first round 79. He had a birdie-birdie start and then gained a stroke at the seventh. But back-to-back bogeys meant he was back to one-under for the day.
However, Kapur, who was the brain behind the inaugural Golf Premier League, said if the current economic situation continues then he would also have to think about the sustainibility of GPL next year.
Kapur had recently stunned the golf world by topping the leaderboard after nine holes on first day at The Open Championship.
Seeing his name up on the leaderboard, albeit for a brief moment in the opening round, will forever be etched as one of the best experiences in his career.
The 31-year-old, who had a dream start with six birdies in seven holes on Thursday, crashed to two triple bogeys and six other bogeys for a three-day total of 15-over 228.