In June 2013, Dufner finished fourth at the U.S. Open at Merion Golf Club, the second year in a row finishing fourth at the tournament. Dufner entered the final round at +8, but birdied five of the first 14 holes to pull to +3 overall. However, he triple-bogeyed the par-4 15th hole to move back to +6. After a birdie at 16, Dufner scored par on holes 17 and 18 to finish the tournament at +5, four shots behind the leader, Justin Rose.