If Phil Mickelson ends up winning the World Golf Championships-Bridgestone Invitational this year, he might have to get a bit creative with how he congratulates people.

Mickelson was noticeably ill following Thursday’s opening round at Firestone, complete with a scratchy voice and bloodshot eyes. He said it’s from giving too many high-fives.

“I’ve got to be careful on some of the high- fives and hand slappings and stuff, because it looks like that’s kind of been the cause of me getting sick a little bit,” he said. “I’ve got to cut some of that out.”

Mickelson said perhaps he could revert to the classic thumbs-up as a congratulatory substitute. A recent study also showed that fist bumps relay 90 percent fewer germs than high-fives or handshakes, so there’s that possibility, too.

“I haven’t been able to physically practice,” Mickelson said. “I’ve been putting and chipping but I haven’t been able to hit a lot of balls.”

Limited practice notwithstanding, maybe Mickelson has some thumbs-ups or fist bumps in his future, considering his history of golfing while sick.

“I played some of my best golf when I was sick, too,” he said. “I remember – well, it’s been a while now, but back in San Diego, like 2000 or 2001, I ended up being in the hospital with an IV on Tuesday or Wednesday and ended up winning.

“I remember doing that at Doral the night before the final round. And you come out and it just kind of slows your mind down. You don’t get ahead of yourself. You don’t rush things. Sometimes you play your best golf like that.”

Mickelson finished his first round with a 1-over 71, seven strokes behind leader Marc Leishman.

Though he easily could have withdrawn in the wake of his sickness, it was important for Mickelson to play because of what lies ahead.

The PGA Championship at Valhalla in Louisville, Ky., begins Aug. 7. Not only does Mickelson want to be ready for the final major championship of the year, it’s his last opportunity to earn Ryder Cup points – and he’s currently one spot out of an automatic qualifying spot.

“If I’m going to have a good chance next week at a golf course I’ve played well at in the past, I needed to get sharp. I needed to get out and play,” Mickelson said.

He said keeping his streak of Ryder Cup teams intact is important to him.