In golf, what is the only major championship to have a full 18-hole playoff in the event of a tie?

The U.S. Open is the only one of the four major championships which retains a full 18-hole playoff the following day (Monday). If a tie exists after that fifth round, then the playoff continues as sudden-death on the 91st hole.

The United States Open Championship, commonly known as the U.S. Open, is the annual open national championship of golf in the United States. It is the second of the four major championships in golf, and is on the official schedule of both the PGA Tour and the European Tour. It is staged by the United States Golf Association (USGA) in mid-June, scheduled so that, if there are no weather delays, the final round is played on the third Sunday, which is Father's Day. The U.S. Open is staged at a variety of courses, set up in such a way that scoring is very difficult, with a premium placed on accurate driving.

The four major tournaments in golf are the Masters, the United States Open Championship, the Open Championship and the PGA Championship.