Sweden's Johan Edfors sprinkled nine birdies in a six-under-par 65 to share the lead with David Drysdale at the Scottish Open.
Edfors and Drysdale took advantage of calm and sunny conditions at picturesque Loch Lomond to move one stroke ahead of Darren Clarke and Miles Tunnicliff.
Jose Maria Olazabal carded a 67 alongside David Bransdon, Raymond Russell and Andrew Butterfield.
Edfors, who won the TCL Classic and British Masters titles earlier this year, made a blistering start with four birdies in the first five holes.
He dropped strokes at the sixth, 12th and 16th but made further inroads on par at the eighth, 10th, 13th, 15th and 18th.
Edfors took time off after being drained by his British Masters victory at the Belfry in May.
'In four weeks I only played two rounds of golf,' he told reporters.
'Then I went down to Paris (for the French Open) and missed the cut. Last week I did a lot of practice with my coach, and on my own as well, and it has paid off.'
Earlier, Clarke explained why Sundays were proving less than fun days for him.
'I am close to playing okay but mentally I am not quite there,' said the 37-year-old from Northern Ireland.
'I am making a few silly mistakes, especially come Sunday. My Sunday score average this year is very, very high, which is totally out of character for me.'
Last week's European Open at the K Club in Ireland typified Clarke's season.
He went into the final round two shots off the pace but a closing four-over 76 ruined his chances and victory went instead to Stephen Dodd.
