The second round was completed only yesterday after a 11-hour disruption due to high-speed winds at the Old Curse at St. Andrews.
Lahiri, winner of Malaysian Open and Hero Indian Open this season, has cards of 69 and 70 in first two rounds and at nine-under through 47 holes, midway through his third round.
He moved into Top-5 and was in line to notch up his personal best at Major and the best by an Indian at any Open Championships.
Lahiri was three-under for the front nine and became four-under after 11 and has been bogey-free for last 30 holes - the last bogey was on par-4 17th Road Hole on Thursday in the first round.
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Lahiri opened with a birdie on the first and then quietly parred the next two before slotting another on the fourth. Four more steady pars were followed by a third birdie on ninth as he turned in an excellent three-under. A fourth birdie came on 11th.
Lahiri had five birdies and two bogeys on day one and then two birdies and no bogeys on second. On the third day it has been three birdies in nine holes against bogeys.
On Saturday with high speed winds hitting the Old Course at St. Andrews, Lahiri had a complete off day as he did not get to play. "It is always nice to get some rest and to get that midway through a Major like Open is a bonus," Lahiri had said. "I am enjoying all this right now."