Rory McIlroy left the Genesis Scottish Open with a sparkling 64 and a clear sense that his game, while close, still needs sharpening before The Open at Royal Birkdale.

McIlroy surged to 12 under with a final round that featured eight birdies and two bogeys, matching his lowest score of the season. It was a powerful response to a stuttering third round of 73 at the Renaissance Club, where fog delays and a misfiring iron game knocked him out of serious contention.

“I definitely hit it a little better today than I did in round three,” McIlroy said after his closing round. He explained that the problems had become obvious as he completed the weather-delayed third round earlier in the day, particularly with his iron play.

Between rounds he headed straight to the range, searching for answers. What he found was a recurring technical flaw that appears in certain winds. “At least I know what the problem is and it’s just about fixing it,” he said. “It’s been pretty windy this week, and when the wind on the range is off the left, I just get into that bad habit of hitting it further left than the path at impact.”

The result is a pattern of iron shots starting and staying left, a miss that crept in again during the final round. “I still hit a few out there today but I managed it a little bit better and I managed the clubface better,” he said. The putter did the rest, transforming a scrappy 73 into a polished 64. “I putted really well today – that was the difference between 73 and 64.”

McIlroy’s round caught fire early, with five birdies in his first seven holes to move within one of the lead. A three-putt bogey at the ninth halted his charge, but he responded with back-to-back birdies from the 12th. When a poor approach at the 16th led to another bogey, the Masters champion muttered that he was “so bad at golf” – a moment of frustration that underlined his exacting standards.

Even so, he left Scotland encouraged. “It’s nice to sign this week off with a good score but I know I need to do a bit of work between now and next Thursday to feel really comfortable with my game. I don’t feel like it’s too far away. There’s definitely some positive signs.”