CBS averaged 9.45 million viewers and a 5.5 rating on Sunday. The previous low for an April Masters was Sergio Garcia's win in 2017, which averaged 11.1 million viewers and a 6.8 rating.
One common denominator for the two lowest-rated April Masters was the absence of Tiger Woods.
However, Dustin Johnson's dominant performance at the 2020 Masters in November remains the least-watched Masters on record, largely because of its unusual spot on the calendar.
The ratings for Matsuyama's win do not account for online streaming or any viewership numbers from Japan.