Thomas Pieters remained in a share of the lead as play was suspended for the second time on day two of the WGC-Bridgestone Invitational.
The start of play had been delayed by 45 minutes on a stormy morning at Firestone Country Club and just two hours and 14 minutes of golf was possible before the hooter sounded to bring the players off for another 46 minutes at 10.29am local time.
Play got back under way for just under two hours before the threat of lightning once more reared its head with Pieters and American Jimmy Walker at the top of the leaderboard on five under.
Pieters had entered the day with a one-shot lead and while he started with two poor shots to bogey the first, he took advantage of the par five next to sit level par for the day after eight holes.
Walker - who will defend his US PGA Championship title next week - picked up three shots in his first ten holes to share the lead and sit a shot clear of Russell Knox, Jason Day and Zach Johnson.
World Number Four Rory McIlroy was then at three under after turning in level par alongside American Charley Hoffman and Canada's Adam Hadwin.
Walker made a fast start with birdies on the second, third and fifth and while he dropped a shot on the seventh, he regained it on the next.
Knox became the first Scotsman to win a World Golf Championships event at the 2015 WGC-HSBC Champions and got off to a blistering start on day two in Ohio.
He birdied the first after an approach to five feet and holed a putt from similar range on the next before a ten-footer on the third moved him to seven under.
Bogeys on the fifth and seventh dropped him back after poor tee-shots on the par threes but a 16-footer on the ninth saw him turn in 33 and lead again before back-to-back bogeys on the 11th and 12th.
Australian Day was compiling the round of the day as he turned in 30 thanks to some stunning putting.
He holed from 22, 25 and 34 feet on the first, third and ninth, while making the most of the second and hitting an excellent tee-shot into the fifth.
Johnson - the 2015 Open champion - made five birdies and two bogeys in his first 15 holes.
McIlroy was another player to capitalise on the gettable second but he failed to get on in regulation and dropped a shot on the ninth.
Hadwin and Hoffman were one under for the day after 15 and 16 holes respectively.
Race to Dubai Rankings presented by Rolex leader Tommy Fleetwood was then at two under alongside Champion Golfer of the Year Jordan Spieth, World Number Three Hideki Matsuyama and American Kevin Kisner.
Hudson Swafford made the 25th hole-in-one of the season and first here since 2011 as he aced the 15th from 214 yards.
Play got back under way for just under two hours before the threat of lightning once more reared its head with Pieters and American Jimmy Walker at the top of the leaderboard on five under.
Pieters had entered the day with a one-shot lead and while he started with two poor shots to bogey the first, he took advantage of the par five next to sit level par for the day after eight holes.
Walker - who will defend his US PGA Championship title next week - picked up three shots in his first ten holes to share the lead and sit a shot clear of Russell Knox, Jason Day and Zach Johnson.
World Number Four Rory McIlroy was then at three under after turning in level par alongside American Charley Hoffman and Canada's Adam Hadwin.
Walker made a fast start with birdies on the second, third and fifth and while he dropped a shot on the seventh, he regained it on the next.
Knox became the first Scotsman to win a World Golf Championships event at the 2015 WGC-HSBC Champions and got off to a blistering start on day two in Ohio.
He birdied the first after an approach to five feet and holed a putt from similar range on the next before a ten-footer on the third moved him to seven under.
Bogeys on the fifth and seventh dropped him back after poor tee-shots on the par threes but a 16-footer on the ninth saw him turn in 33 and lead again before back-to-back bogeys on the 11th and 12th.
Australian Day was compiling the round of the day as he turned in 30 thanks to some stunning putting.
He holed from 22, 25 and 34 feet on the first, third and ninth, while making the most of the second and hitting an excellent tee-shot into the fifth.
Johnson - the 2015 Open champion - made five birdies and two bogeys in his first 15 holes.
McIlroy was another player to capitalise on the gettable second but he failed to get on in regulation and dropped a shot on the ninth.
Hadwin and Hoffman were one under for the day after 15 and 16 holes respectively.
Race to Dubai Rankings presented by Rolex leader Tommy Fleetwood was then at two under alongside Champion Golfer of the Year Jordan Spieth, World Number Three Hideki Matsuyama and American Kevin Kisner.
Hudson Swafford made the 25th hole-in-one of the season and first here since 2011 as he aced the 15th from 214 yards.
