The US Open is set to get underway at Pebble Beach, California on Thursday. American Brooks Koepka won the event last year at Shinnecock Hills, finishing on one over after four rounds, one shot clear of Englishman Tommy Fleetwood. Koepka, along with Masters champion Tiger Woods, Rory McIlroy, Dustin Johnson, Francesco Molinari and Jordan Spieth have all been listed as potential winners of the third major of the year. However, with 156 players set to take to the course on Thursday, we’ve taken a look at 20 players who could cause an upset in California and lift the prestigious trophy.