Phil Mickelson retained control of the 145th Open Championship with a second-round 69, as the likes of Henrik Stenson and reigning champion Zach Johnson improved their positions at Royal Troon.
A stunning 63 from Mickelson had provided the highlight of an opening day that saw countless players take advantage of benign conditions.
However, bright blue skies gave way to persistent rain on Friday and an even tougher challenge was in prospect for the later starters, with winds expected to strengthen in the afternoon.
Mickelson therefore held a strong hand having reached the clubhouse at 10 under, two clear of Stenson, who was five under for his second round with three holes to play.
Soren Kjeldsen (68) and Johnson were a shot further back, while Patrick Reed - who headed the leaderboard for much of the first day - had just begun his second round trailing by five.
If Reed and the likes of Justin Thomas (-4), Justin Rose (-3) and Rory McIlroy (-2) had work to do given the weather forecast, Jordan Spieth (E) and Jason Day (+2) were in danger of being out of contention as they prepared to tee off again.
It's raining and yup, Phil's two gloves are out pic.twitter.com/skJ3EXBWTs-- The European Tour (@EuropeanTour) July 15, 2016
The champion at Muirfield three years ago, Mickelson initially opened up a five-stroke advantage at 11 under on Friday when birdies at the fourth and seventh were followed by his second successive gain on the short eighth - the left-hander again coming close to a hole-in-one at the Postage Stamp.
Errant tee shots at 12 and 15 saw the leader finally drop his first shots of the tournament, but those errors came either side of another birdie on the 14th - his fifth two of the week.
After Stenson had closed to within two by birdieing the 13th, Mickelson then produced a superb up-and-down from a greenside bunker to save par on 17, before making four at the last to complete another fine day's work.
Martin Kaymer and Keegan Bradley each made it to seven under before slipping back, the former dropping four shots in two holes at the start of the inward nine.