The reigning Asian Tour number one struggled on the greens on yet another blustery day at Royal Troon, needing 32 putts which included three putting on three occasions as he fell off the pace in the year's third Major.
A double bogey on the second hole set the tone for Lahiri's difficult day. A birdie on four was the Indian's only respite as he dropped three straight bogeys from the 10th hole before missing a short par attempt at the last.
"I guess I've got to work on my putting. I didn't hit it that bad, conditions weren't easy but it's just that I left so many shots out there on the greens. I'm very disappointed."
Lahiri is determined to pick himself up tomorrow and finish strongly. He knows he must regain his confidence with the flat stick, which he conceded has been a bane all season.
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"I'm very proud of myself. I don't think I need to feel bad. I'm going through a phase where I'm not making any putts," said the 29-year-old.
"When conditions are like this, it's difficult to keep it in play, it's difficult to get it on the greens and I've done all the difficult parts. It's getting the ball into the hole which seems to escape me right now.
"It's frustrating to a point where I have to find it somewhere," added the Indian, who is making his fourth appearance in the world's oldest Major.