Dustin Johnson is refusing to get carried away after he shot an impressive 66 to take the lead after the first round of the US PGA Championship at Whistling Straits.

The 31-year-old, who has been one of the most consistent players in the world this year, holds a one-shot lead over David Lingmerth of Sweden, while Jason Day and Matt Kuchar were in a large group that carded 68.

Johnson finished in a tie for sixth at the US Masters in April before clinching joint-second spot at the US Open and has been in the lead after five of the 13 rounds this year in the majors without actually winning any of the tournaments.

“We’ll just have to see what happens,” Johnson said. “It’s only the first round. We’ve still got a lot of golf to play.”

Both Rory McIlroy and Jordan Spieth, who have won four of the last five majors, shot 71 in the blustery conditions.

It was McIlroy’s first round of competitive golf for almost two months because of an ankle injury, while Masters and US Open champion Spieth started with 10 straight pars and did not pick up a birdie until the 12th hole after bogeying the 11th.

“I really battled back after the 11th hole to stay in this tournament,” Spieth said. “If I didn’t get that good break on 12, it could have been a different story the rest of the round.”

Johnson is 5.50 to win the US PGA Championship outright while Day can be backed at 7.00 and Spieth is 8.50.