Aaron Wise revealed he learnt plenty from a practice round with "the calmest person in the world" Brooks Koepka in the lead up to the U.S. Open on Thursday.

Wise carded a five-under 66 at Pebble Beach, sitting in a four-way tie for second and a shot behind outright leader Justin Rose.

The American practised with two-time defending champion Koepka on Tuesday and said he took plenty from his countryman's mentality.

"Maybe just some strategy stuff I can take from him. More me and Brooks have just become good friends in a way and enjoy each other's company," Wise said after his first round.

"And on top of maybe just a strategy, something I can take away from him is just his calmness, not only just playing in those practice rounds but I've seen him multiple times through the events like today when I was on 17 tee he was on four tee. And just saying hey.

Make way …@AaronWise_ moves to 5-under, joining Fowler, Schauffele and Oosthuizen atop the leaderboard. pic.twitter.com/MYRLJHdAnK
— PGA TOUR (@PGATOUR) June 13, 2019

"And he's literally the calmest person in the world. It's just a calming influence and I can kind of just take away his mentality towards these [events], and the fact that he really slows things down and calms things down even more and that works well for him."

Wise, Rickie Fowler, Xander Schauffele and Louis Oosthuizen carded 66s in favourable conditions on Thursday.

Oosthuizen, the 2010 Open Championship winner, said success at the U.S. Open would be incredible.

"I think just winning a major is already to me sacred enough. To be able to win a U.S. Open would be very magical to me," the South African told a news conference.

"It would be I think something that anyone can dream of winning an Open and the U.S. Open. I think Pebble to me is probably one of my favourite, if not my favourite venue for a U.S. Open.

"You're not going to beat the scenery and everything about this golf course, and it's just the weather we're having at the moment, it makes this week really special."

Blind birdie.@Louis57TM holes out on his final hole to tie @RickieFowler and @XSchauffele for the lead at -5.

It's his second hole-out of the day. pic.twitter.com/vU23K04u98
— PGA TOUR (@PGATOUR) June 13, 2019