The world No.5 underwent knee surgery in September and withdrew from Woods' tournament in the Bahamas last week, which the team used to fine-tune Cup preparations.

But the 35-year-old, who was the highest-ranked American until slipping a spot behind Justin Thomas this week, said he was available to play as many matches as Woods demanded.

"I'll play as many as Tiger wants me to play - I wouldn't be here if I wasn't ready to play," Johnson said on Wednesday.

The long-time world No.1 impressed his teammates and captain's assistants Steve Stricker and Zach Johnson during practice, particularly given his long lay off.

"He looks great out there," Stricker said of 2016 US Open champion, who is gunning for his fourth Presidents Cup title.

"He's hitting it a long way, as he normally does.

"His knee is not an issue at all - he's feeling good and hitting it well."

Fellow assistant Zach Johnson said there was a buzz amongst the US team.

"On first day out everybody kind of had a little bit of fog there early but the last 12 holes, even the guys he was playing with are like, 'Oh, someone's back'," Zach Johnson said.

Johnson was in stellar form early in 2019, finishing runner up in both the Masters and PGA Championship with his form dip coinciding with his knee trouble.

"Obviously I had a pretty good start to the season but in the back half, I was struggling a little bit," Johnson said.

"What I was struggling with in my golf swing, you definitely could relate it to the knee with what I was doing, which was hanging back too much and just not controlling the golf ball well enough."

While stacked with top 20 players, the US team will be relying on Johnson's experience, with only veteran Matt Kuchar and playing captain Woods taking part in more Presidents Cup tournaments.

The trio, as well as Webb Simpson, were part of the 2011 team that won at Royal Melbourne.

Australian Associated Press