The U.S. Open uses a two-hole aggregate playoff to determine its champion.
In this format, if two or more players are tied after 72 holes of regulation, they will compete over two additional holes with the player producing the lowest total score winning. If players are still tied, sudden death is used.
For this year’s edition at Oakmont Country Club, the two holes will be Nos. 17 and 18. If sudden death is warranted, it will begin on the 15th hole.
The USGA implemented the two-hole system in 2018, altering it’s long-standing 18-hole playoff. There has not been a U.S. Open extra session since the change.
The most recent of 33 U.S. Open playoffs was in 2008, when Tiger Woods defeated Rocco Mediate over 91 holes, needing sudden death, on top of the additional 18, at Torrey Pines.
As for the other men’s major playoff formats, the Masters uses sudden death, the PGA Championship a three-hole aggregate and The Open a four-hole aggregate.