Dustin Johnson is next on the oddsboard, at 5-to-2, followed by Jason Day (4/1) and Branden Grace (6/1). Spieth, Johnson, Day and Grace are all 4-under par after the third round.
With the Open taking place at Chambers Bay in University Place, Washington, the final round tees off at a betting-friendly time of 10:55 a.m. ET, and the leaders don’t get started until 5:48 p.m. ET (Spieth, Grace) and 6 p.m. ET (Johnson, Day).
More: What leaders need to do | Tee times
ODDS TO WIN 2015 U.S. OPEN (updated after third round): JORDAN SPIETH 7/4 DUSTIN JOHNSON 5/2 JASON DAY 4/1 BRANDEN GRACE 6/1 LOUIS OOSTHUIZEN 20/1 J.B. HOLMES 25/1 SHANE LOWRY 30/1 HENRIK STENSON 60/1 CAMERON SMITH 80/1 PATRICK REED 80/1 BRANDT SNEDEKER 100/1 TONY FINAU 150/1 JOOST LUITEN 200/1 ANDRES ROMERO 250/1 FIELD (all others) 25/1