Dustin Johnson is relishing his rivalry with friend and two-time reigning U.S. Open champion Brooks Koepka at Pebble Beach.
Koepka is bidding to win a third consecutive U.S. Open title in California, where the world number one is coming off success at the US PGA Championship.
The 29-year-old won the US PGA by two strokes ahead of Johnson, who lost his top ranking to Koepka as a result last month.
Johnson and Koepka have a strong relationship but the two American are rivals on and off the golf course.
"Yeah, Brooks is one of my best friends. Yeah, we compete," Johnston told reporters on Tuesday, ahead of Thursday's opening round.
"Doesn't matter what we're doing, we're competing doing it."
Johnson won his lone major at the 2016 U.S. Open at Oakmont, and the 34-year-old will look to begin the journey to a second this week.
A 20-time PGA Tour champion, Johnson is content with competing at a familiar venue and is among the favourites to emerge victorious at Pebble Beach.
"I like the golf course. I know the golf course very well playing the AT&T every year, playing the 2010 Open here," Johnson said. "It's a golf course that I'm very comfortable on. Obviously this time of year it plays much different than it does in the AT&T, but it still is very helpful to know the golf course."
Johnson has performed well at majors this year – finishing tied for second at the Masters and while he was runner-up to Koepka at the US PGA.
"I feel like I've had good work Monday, good work today," Johnson said. "I'm seeing the patterns that I want to see. For me, if I can — I feel like the putter is starting to roll really good. Last week it was tough to tell how you were putting last week."