Three dropped shots later, Lane trudged off the 18th green in sixth place.
A journeyman player whose victory at the British Masters in May was his first in nine years, Lane was tied with Todd Hamilton when he left the 16th. He was just ahead of Masters winner Phil Mickelson and U.S. Open champion Retief Goosen, with Ernie Els and Tiger Woods not far behind.
After his double bogey at the par-3 17th and bogey 5 on the final hole, he was behind Els, Mickelson and Goosen and just one stroke ahead of Woods.
'Yesterday I finished 2-3. Today I finished 5-5,' Lane said. 'A five shot difference.'
Three-time British Open winner Nick Faldo picked up England's last victory in 1992 at Muirfield. An Englishman hasn't won at Troon since Arthur Havers did so in 1923.
'The thing is, you hit one bad shot. It was 17, I just pulled it,' Lane lamented. 'It must have pitched just on the bank and gone left. I had a very, very tough chip just to get onto the green. I just hit it too far up the bank and it obviously went over the green. End of story.
'Then, at the last hole, I just pulled a 6-iron a little bit, the wind was a bit stronger off the left and it went into the bunker.'
Lane's shot from the sand wound up 12 feet from the flag and he missed the putt to finish with three 5s. There was nothing in Lane's record to suggest he would be a threat at Royal Troon.
In 12 British Opens, he had missed the cut six times and his best finish was 13th at Royal St. George 11 years ago.
His victory at the British Masters came 10 years after his last European Tour victory, although he won the Andersen Consulting World Championship in 1995.
After two rounds at Troon, Lane was two strokes behind leader Skip Kendall in a tie for third place, only to fall back after a bogey 5 on the second hole.
But he picked up strokes at the sixth and eighth to reach the turn in 35 before charging into a share of the lead with three birdies between the 12th and 15th.
As he climbed to the top of the leaderboard, English fans following his round began to build up the noise level. It's not something he's used to, especially in Scotland.
'The crowds have been unbelievable,' he said. 'You get cheered. You get clapped onto every tee, cheered onto every green. Everyone is shouting your name.
'A couple of guys had had a few beers, they were chanting 'Barry Lane' on the way round. The atmosphere is fantastic.
'You have to try and enjoy it, but it is difficult because you're out there trying hard.'
On Sunday, he will have to try harder.
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