First became world No 1 in February 2017 with a 13th PGA Tour victory and on his next two starts added his fourth and fifth World Golf Championships.
Only Tiger Woods has been more successful in the series, but with his Dell Match Play win Johnson became the first to capture all four WGC events.
At the 2016 US Open he came from four behind Shane Lowry after 54 holes to win by three, even with a one-stroke penalty for his ball moving a fraction as he prepared to putt. In the same event 12 months earlier he three-putted the 18th to lose by one to Jordan Spieth.
Also led the 2010 PGA Championship before being handed a two-stroke penalty for grounding his club in what was controversially deemed to be a fairway bunker on the final hole.
Johnson, joint runner-up with Phil Mickelson behind Darren Clarke at The Open in 2011, is a four-time Ryder Cup and three-time Presidents Cup player. After losing top spot on the rankings to Justin Thomas in May 2018 he regained it a month later with a six-shot victory at the FedEx St Jude Classic and a week later was third at the US Open.