The last two U.S. Open winners are both 1 over par after the first round at Royal St. George's, along with defending champion Shane Lowry. Thomas is 2 over par.
Louis Oosthuizen leads the way at Royal St. George, with Jordan Spieth and Brian Harman a shot further back.
World No. 1 Jon Rahm is the bookmakers' favorite as he looks to win a second consecutive major.
The Spaniard won his maiden major after shooting 4-under par in the final round at Torrey Pines on Sunday.
The reigning PGA Championship winner shot 4-over par in the opening round, while three-time major winner Jordan Spieth finished at 6-over par.
Corey Conners is the bookmakers' favorite at 7-1 after taking a two-shot lead in the first round at Kiawah Island.
Canada's Corey Conners leads by two strokes after shooting a 5-under par 67 in the first round, with Brooks Koepka and Phil Mickelson two and three shots behind.
Rory McIlroy is the bookmakers' favorite to win the second major of the season, followed by Jordan Spieth and Jon Rahm.
England's Justin Rose leads the field by four shots after carding a 7-under-par 65 on Thursday, while defending champion Dustin Johnson finished a 1-over-par.
Johnson posted scores of 65 on Thursday and Saturday, becoming the first golfer to ever shoot two rounds of 65 or lower in the same Masters tournament.
First-round leader Justin Thomas tees off at 1:27 p.m. ET alongside 15-time major winner Tiger Woods.
Justin Thomas leads the U.S. Open by one shot after carding a 5-under 65 in the first round on Thursday.
The first round of the U.S. Open gets underway at 6:50 a.m. ET on September 17, with world No.1 Dustin Johnson set to hit his first tee shot shortly after 1 p.m. ET.
World No. 1 Dustin Johnson is the man to beat in the second major of the season, with No. 2 Jon Rahm and No. 7 Xander Schauffele among his leading rivals.
Dustin Johnson begins the final round of the PGA Tour season finale with a five-shot lead over Justin Thomas and Xander Schauffele.
World No.1 and FedEx Cup leader Dustin Johnson arrives at East Lake as the man to beat this weekend.
The FedEx Cup's top-30 ranked players all feature in the season finale of the PGA Tour season, which begins on Friday in Georgia.
FedEx Cup leader Dustin Johnson will start the season finale at 10-under, two shots ahead of world No.2 Jon Rahm.
Tiger Woods will begin the second round at 4:58 p.m. ET alongside world No. 1 Justin Thomas and Rory McIlroy.
Brooks Koepka trails the leaders by one shot after the first round, while Tiger Woods is two shots further behind in his second start since February.
The 15-time major winner has been paired with world No. 1 Justin Thomas and four-time major winner Rory McIlroy for the first two rounds.
The first major of the season begins at TPC Harding Park in San Francisco on Thursday as Brooks Koepka looks to win a third consecutive title.
Brooks Koepka is the bookmakers' favorite to win the tournament for a third consecutive time, with world No.1 Justin Thomas close behind.
The first major of the golf season gets underway on Thursday at TPC Harding Park in San Francisco, California.
Brooks Koepka posted his lowest score on the PGA Tour in four years as he took a two-shot lead at TPC Southwind.
Nine of the world's top-10 ranked golfers are in action at the WGC-FedEx at TPC Southwind in Memphis this week.
World No. 1 Jon Rahm has been paired with Rickie Fowler and Bryson DeChambeau for the first two rounds at TPC Southwind this week.