Finland's Mikko Korhonen withdrew from next week's US Open tournament on Wednesday due to travel concerns, the US Golf Association announced.
The 40-year-old Finn was among 10 players who earned an exemption into the year's third major tournament, to be played at Torrey Pines on June 17-20, through the European Tour qualifying series.
Korhonen will be replaced in the field by 21-year-old US amateur Cole Hammer, the first alternate from the Columbus, Ohio final qualifying site.
Korhonen won the 2018 Austrian Open and 2019 China Open on the European Tour. He missed the cut in the 2018 and 2019 PGA Championships and shared 63rd at the 2019 British Open in his only major starts.
Hammer, a junior at the University of Texas, will make his third US Open appearance after a debut at age 15 in 2015 at Chambers Bay.