Louisville: At the rate American golf stars are getting hurt, Tom Watson might become a playing captain when his US Ryder Cup squad tries to reclaim the trophy from Europe next month.

Sixth-ranked Matt Kuchar, already set for the roster based on qualifying points, withdrew before Thursday’s start of the PGA Championship at Valhalla with back spasms.

Dustin Johnson had been set for a spot before announcing last week he would taking a leave of absence through the end of the year, with a Golf.com report saying he tested positive for cocaine and was set for a suspension.

And defending champion Jason Dufner lasted only 10 holes before walking off the course because of neck pain that has nagged him since the Masters.

Add the struggles of 14-time major champion Tiger Woods with back surgery in March and a withdrawal last Sunday due to back spasms and it seems like the Americans will be lucky to have a healthy 12-man roster for the September 26-28 showdown at Gleneagles, Scotland.

“We’re falling like flies,” Watson said. “We really are.”

Watson helped his cause on the eve of the tournament by naming 23rd-ranked Steve Stricker, 47, as an assistant captain. He could be called upon to play as an injury replacement any time before the Ryder Cup opening ceremony.

“All these guys are dropping like flies on our team and it is a bit scary,” Stricker said after a first-round 69.

“It doesn’t bode well for us so far, but there are a lot of good players still and guys are still jockeying for position and trying to make that team.”

Watson won’t actually be playing, although the 64-year-old legend who won eight major titles nearly picked up his sixth British Open crown in 2009 at Turnberry before settling for second and is beloved enough to steal some support in Scotland.

What he will have to do is figure out who to make his three captain’s selections on September 2 after seeing who makes the team on points after Sunday’s final round of the year’s last major.

“There’s time,” Watson said. “What’s going to happen between now and then is anybody’s guess. I have to take the information I have, process it and see what comes out.”

He already joked with Stricker on Thursday, saying in the wake of so many US troubles that Stricker “better get your clubs ready.”

Stricker needs a high finish to make the team on points.

Pressure players wanted

Watson is watching to see who handles the tension in this week’s major test.

“Who performs under pressure — that’s what I’m looking for,” Watson said.

Already assured of spots on points are Masters winner Bubba Watson, 2013 PGA runner-up Jim Furyk, US and British Open runner-up Rickie Fowler, Jimmy Walker and Kuchar, while Jordan Spieth is all-but assured a spot.

The other positions are held by Patrick Reed, Zach Johnson and Dufner, but hot on their heels are five-time major winner Phil Mickelson and former PGA champion Keegan Bradley.

Mickelson has vowed to make the squad on points rather than be a captain’s choice.

Watson has said he will select Woods if he is healthy. Woods had no back issues on Thursday was fired a 74 and could miss the cut, likely ending his season and leaving a long gap with no events ahead of the Cup.

“I know Tiger wants to be part of that team and we can definitely use him with guys getting hurt,” Stricker said. “We just have to wait and see how he feels.”