The second round of the 2019 U.S. Open will be crucial for some players to improve their positioning ahead of the weekend.
Justin Rose is in the best shape of the 156 golfers in the field, as he holds a one-shot advantage over a collection of players in second place.
If you look further down the leaderboard, there are plenty of experienced players who could make a second-round surge, including two-time defending champion Brooks Koepka, who did just that a year ago.
There are also some high-profile players that need to make improvements from Thursday's first round in order to have a chance of being in contention for the title Saturday and Sunday.
U.S. Open Leaderboard
Justin Rose (-6)
Aaron Wise (-5)
Rickie Fowler (-5)
Xander Schauffele (-5)
Louis Oosthuizen (-5)
Scott Piercy (-4)
Full leaderboard can be found on USOpen.com.
Friday Storylines to Watch
Will Koepka Make His Surge Into 1st?
A year ago at Shinnecock Hills Golf Club, Koepka used a second-round 66 to make his presence known on the leaderboard.
The difference between 2018 and 2019 is Koepka performed well enough in the first round at Pebble Beach to set himself up for a surge into first place.
The two-time defending champion started his tournament with a first-round 69 that puts him four shots back of current leader Justin Rose.
In his last four second rounds at tournaments, Koepka is averaging a score of 66.25, with the worst total being a 68 at the Zurich Classic.
All of those numbers lead us to believe Koepka is line for a surge up the leaderboard Friday that puts him in one of the final groups for Saturday's third round.
In order for that to happen, Koepka needs a better performance on the back nine, where he will start his second round.
On Thursday, Koepka bogeyed No. 13 and No. 17 after reeling off five birdies on his first 12 holes.
If Koepka produces a steady hand on the back nine to start his round, he could take advantage of the front nine once again to land at, or near, the top of the leaderboard.
Can Johnson and Spieth Rebound From Tough Opening Rounds?
Two of the noticeable names missing from the top of the leaderboard are Dustin Johnson and Jordan Spieth.
Johnson shot an even-par 71 that featured an up-and-down back nine in which he picked up three birdies, two bogeys and a par from No. 13 to No. 18.
Spieth was visibly frustrated with his play, as he bogeyed three out of four holes to finish the front nine.
Luckily for Spieth, he was able to recover from the poor stretch and end the round with a one-over 72.
While neither player had horrific first rounds, they still showed signs of weakness that could doom them Friday.
Based off recent results on the PGA Tour, Johnson appears to be in better shape of climbing up the leaderboard than Spieth.
In his four tournaments prior to the U.S. Open, Johnson recorded a single round over 70, and he has carded a second-round score in the 60s in eight competitions this season.
On the other hand, Spieth has been a bit more inconsistent, especially in the rounds that matter the most.
Spieth has not carded a score under 70 in the final round of his last four tournaments, and he failed to crack the 60s in two rounds at the PGA Championship in May.
If Spieth produces a similar performance to Thursday's back nine, where he had eight pars and one birdie, he will be in better shape, but if the frustration continues to seep through and he goes through a bogey stretch, he might be in danger of missing the cut.
Follow Joe on Twitter, @JTansey90