The Americans' mutual dislike is no secret and Koepka recently offered beer to fans who were ejected from the Memorial Tournament for heckling DeChambeau.

A video where Koepka had to stop an interview because he was so exasperated with a sarcastic comment made by DeChambeau in the background also went viral in recent weeks.

To the disappointment of many, DeChambeau and Koepka have been kept apart in the groupings for the first two rounds in California, but both are in blockbuster three-balls largely made up of major winners.

DeChambeau is to play alongside compatriot Tyler Strafaci and Japan's Hideki Matsuyama, the reigning Masters champion.

Koepka, who won the 2017 US Open at a record 16 strokes under par, will play with fellow Americans Justin Thomas and Collin Morikawa, who have both won a major before.

Northern Ireland's Rory McIlroy - a four-time major winner who opened his account at the 2011 US Open, at a record 16 strokes under par - and Englishman Justin Rose, who won the Rio 2016 gold medal for Britain, are to play with world number one Dustin Johnson of the United States.

Another player with plenty of attention on him will be Spain's Jon Rahm, who led the Memorial Tournament by six shots after 54 holes a fortnight ago, only to test positive for COVID-19 and have to withdraw.

Rahm has returned negative coronavrius tests to be cleared to play at Torrey Pines.

He is in a group with Australian Marc Leishman and American Patrick Reed, who is a former Masters winner.

New PGA Championship champion Phil Mickelson, 51 today, is in a group with fellow US players Xander Schauffele and Max Homa.

The US Open has been played at Torrey Pines once before, in 2008, when Tiger Woods won in an all-American playoff versus Rocco Mediate.