England's Danny Willett shrugged off two late three-putt efforts to set the early clubhouse target on 9-under-par in the weather-interrupted second round of the 144th British Open on Friday.
After a torrential downpour left pools of water lying all over the iconic St Andrews layout and caused play to be suspended for three hours and 14 minutes, it started to rain birdies for double European Tour winner Willett.
The 27-year-old, who missed the cut in two of his three previous Open appearances, picked up strokes at the second and fifth holes before coaxing in a birdie effort of 25 feet at the ninth.
Another birdie followed at the 10th for Willett before he three-putted the 15th and 17th, his par-saving effort at the infamous Road Hole horse-shoeing out.
However, he hit straight back by knocking in an eight-foot birdie effort at the last to post a 3-under 69 for a total of 135.
That gave Willett a two-stroke lead over 2007 U.S. Masters champion Zach Johnson (71) and Scotland's Marc Warren (69).
Overnight leader Dustin Johnson, who does not get his round underway until 5:48 p.m. local time, is 7 under, two in front of playing partner Jordan Spieth.
The 21-year-old Spieth is attempting to become the first player since fellow American Ben Hogan in 1953 to win the first three majors of the season.
Following the early rain delay and a copybook mopping up operation from the 100-plus groundstaff, play restarted at 1000.
An hour later there was little sign of what had gone before as the sun began to shine on the east coast of Scotland, the wind died down and the puddles disappeared.
Earlier, the greens, fairways and bunkers were saturated and the few brave fans in attendance were huddled in the exposed rain-lashed grandstands.
Sand bags were needed to prevent floodwater entering the media center.
The early starters are likely to have the better of the conditions because forecasters say the wind is expected to return with a vengeance later, gusting up to 35mph.
Saturday's forecast is for even stronger winds, with gusts of around 50mph, meaning organizers could face a difficult task to get the tournament finished on schedule by Sunday.
The second round is almost certain to spill over into Saturday.
The Open was also hampered by bad weather when it was last held at St Andrews in 2010, with dangerous high winds causing havoc in the second round.
(By Tony Jimenez; Editing by Alan Baldwin and Martyn Herman)