The conditions and pin positions at Winged Foot Golf Club have been much tougher for the second round of the 2020 U,S, Open. 

Fewer than 10 golfers in the morning wave of threesomes currently have under-par rounds. A bulk of them have dropped shots with the wind changing direction and the holes in tougher spots. 

Dustin Johnson and Bubba Watson make up part of the group in red numbers, but they have not played well enough to catch first-round leader Justin Thomas yet. 

Thomas Pieters eclipsed Thomas at one point, but the Belgian gave back a shot on the first two holes of the back nine to drop back. 

Thomas will get a chance to defend his lead during the afternoon session. Patrick Reed and Rory McIlroy will try to keep their positions on the leaderboard during the second wave of golfers as well.

US Open Leaderboard

Justin Thomas (-5)

Patrick Reed (-4)

Thomas Pieters (-4)

Rory McIlroy (-3)

Matthew Wolff (-3)

Jason Kokrak (-2)

Harris English (-2)

Brendon Todd (-2)

Tony Finau (-2)

Leaderboard up to date as of 10:40 a.m. ET.

Full leaderboard can be found on PGATour.com.

Storylines to Watch

How Difficult Will Winged Foot Play? 

Low scores have been difficult to find throughout the morning session.

Jon Rahm, Matthew Wolff, Xander Schauffele and Rickie Fowler are among the golfers sitting at par or worse in their respective rounds. 

The difficulty experienced Friday is closer to the conditions we expected to see at Winged Foot. 

The notoriously tough course featured more scores in red numbers than expected Thursday, which led to Thomas recording the lowest-ever U.S. Open round in the course's history.

If the conditions hold in the afternoon, it could be tough to maintain that pace. Some of the best golfers from Thursday have already experienced a drop out of the top 10, including Fowler, Louis Oosthuizen and Joaquin Niemann.

Friday's struggles mean those players have less of a chance to take home the U.S. Open trophy. In the previous five years, the U.S. Open winner has come from a top-five finish after 36 holes. 

Can Justin Thomas Remain In Position To Win? 

Since 2015, each U.S. Open champion has either led or finished in the top five after 36 holes. 

The largest deficit any of those winners made up in the final 36 holes was five shots. Brooks Koepka took advantage of Dustin Johnson's third-round 77 at Shinnecock Hills Golf Club in 2018 to take a share of the lead in the third round and then win. 

A year ago, Gary Woodland entered the weekend with a two-stroke lead that he eventually turned into a three-shot winning margin. 

The key for Thomas will be consistency. If he can shoot an even-par round in the afternoon, he should be in terrific shape to take the title Sunday. Thomas' opening-round scorecard suggests he can keep a steady hand, as he had 11 pars, five birdies and a single bogey. 

Follow Joe on Twitter, @JTansey90.

Statistics obtained from PGATour.com.