The British Open champion scored two late birdies to snatch the lead away from Johnson who struggled uncharacteristically, posting his first ever over-par for the first time in 14 rounds he has played for LIV thus far.
After two rounds Cameron Smith has a total score of 10-under-134 as he looks to win LIV Chicago for his first win on his new circuit.
Peter Uihlein, the former U.S. Amateur champion, raced up the leaderboard after carding the lowest score of the second round with a 66. He sits three shots behind the leading Smith heading into the final day.
Laurie Canter (68) and Charl Schwartzel (69), who won the first LIV Golf Invitational outside London, are tied for fourth four shots behind while Lee Westwood, Charles Howell III and Bryson DeChambeau are part of the group sitting tied for 6th five-strokes back.
Phil Mickelson, who has been making headlines for all things other than his play, struggled once again towards the end with three bogeys in a four-hole stretch and fell 12 shots behind.
In the team competition, Johnson’s four-man squad had a one-shot lead over Smith’s team, with Uihlein’s great round helping put his team — Brooks Koepka is captain — two shots behind.