Fowler completed his round of 62 just before Schauffele at the 2023 US Open.

There have been a further 40 instances of golfers shooting rounds of 63 in Majors, the first being Johnny Miller (USA) in the fourth round of the 1973 US Open at Oakmont. The most recent was in 2026 when Kurt Kitayama (USA) shot a 63 at the USA PGA Championshsip at Aronimink

The only men to complete two rounds of 63 or less are:
Xander Schauffele (above)
Shane Lowry (Ireland), 2019 British Open (63) *, 2024 PGA Championship (62)
Brooks Koepka (USA), 2018 Masters (63) *, 2019 Masters (63) *
Greg Norman (Australia), 1986 British Open (63) *, 1996 Masters (63)
Tommy Fleetwood (England), US Open 2018 (63), 2023 (63)
Vijay Singh (Fiji), 1993 PGA Championship (63), US Open 2003 (63)

The first golfers to shoot 63 in each of the Majors were:
US Open: Johnny Miller (USA) * 1973, Oakmont
PGA Championship:  Bruce Crampton (Australia) 1975, Firestone
British Open: Mark Hayes, 1977, (USA), Turnberry
US Masters: Nick Price (Zimbabwe) 1986, Augusta

Progressive Record
74 Horace Hutchinson (Scotland). 1892 British Open                     
73 Hugh Kirkaldy (Scotland), 1892 British Open                           
72 Harold Hilton (England) *, 1892 British Open                           
71 James Sherlock (England), 1904 British Open                           
69 James Braid (Scotland), 1904 British Open                           
68 J. H. Taylor (England), 1904 British Open                           
67 Willie Macfarlane (Scotland) *, 1925 US Open
65 Henry Cotton (England) *, 1934 British Open                           
64 Lloyd Mangrum (USA), 1940 Masters
63 Johnny Miller (USA) *, 1973 US Open
62 Branden Grace (South Africa), 2017 British Open