World No 1
"It was definitely very satisfying," Johnson said of his playoff win.
"I feel like I played pretty solid all week. It was something that I wanted to accomplish during my career."
Johnson has never played the 7 477-yard Winged Foot layout, which last hosted a major at the 2006 US Open won by Australian Geoff Ogilvy.
The US Open was postponed from June and qualifying was wiped out due to the Covid-19 pandemic. A field of 144, the smallest since 1932, was selected by exemption categories.
The tournament is also taking place without spectators, something players have had to get used since the golf circuit resumed after pandemic shutdown in June.
"Hopefully this is the only one that it's going to happen, and we can get back to somewhat normal life next year and crowds are allowed back," said Northern Ireland's Rory McIlroy. "But it has to be this way for a while, unfortunately, but hopefully not for too much longer."
It's also the first time the US Open will be played outside of June since 1931. It was last played in September in 1913, when amateur Francis Ouimet won in a playoff. No first-time player has won the US Open since.
'Sort of like boxing'
World number two Rahm meanwhile is chasing a first major victory as well as a piece of history. No Spanish player has ever prevailed in the major billed as "the toughest test in golf."
Rahm, who missed the cut at the US Open in 2018 and 2017, is all too aware of the difficulties in plotting a game plan.
"It's sort of like in boxing where Mike Tyson said everybody has a plan until they get punched in the face," Rahm said.
"It's the same thing here. We all have a plan, but if you hit it sideways, you got to figure it out."
Fifth-ranked Morikawa, 23, brings momentum from his first major title.
Morikawa, who will be playing in only his third major, says his PGA win has left him hungry for more success.
"I've only done it once, but I've done it," he said on Tuesday.
"You just want more. You get that little taste of what it's like, and you know why guys mark in their calendars the major championships for the year."
Third-ranked Justin Thomas, runner-up at the Tour Championship, won three titles last season, including last month's WGC St Jude Invitational.
The American, who won his lone major at the 2017 PGA Championship, says Winged Foot is "probably the hardest golf course I've ever played."
"Tee to green, the rough, the greens, everything factored in, I think this is the hardest course I've played," he said.
It's a verdict shared by former world number one Woods.
The 15-time major champion missed the cut at Winged Foot at the 2006 US Open - the only time in 46 consecutive major appearances between 1997 and 2008 that he failed to reach the third round.
"This golf course is going to be one of the more difficult ones," Woods said on Tuesday after a practice round.
"The winning scores here have never traditionally been very low. I don't see that changing this week," added Woods, who will tee alongside Morikawa and Thomas in Thursday's first round.