Courtesy: Warren Little/Getty Images

The 122nd U.S. Open kicked off Thursday morning, and the leaderboard may surprise you.

Canadian golfer Adam Hadwin leads the field after Round 1, shooting a four-under-par 66.

Hadwin’s appearance in this year’s U.S. Open only came to be when Paul Casey withdrew due to an injury. Being the alternate, Hadwin gained his pass to play.

Although Hadwin isn’t new to playing in majors, he still has a lot of golf to play if he wants to keep his lead.

Trailing behind for second place is four-time major champion winner Rory McIlroy.

He ended his round shooting a three-under-par 67.

After coming off his win last week at the RBC Canadian Open, McIlroy is on the hunt for another win.

Three more rounds are still left to play this week, and it could be anyone’s game.

To watch tomorrows coverage of the U.S. Open, viewers can watch on the USA Network from 9 a.m. to 4 p.m. or on NBC from 4 p.m. to 7 p.m.