Dustin Johnson concerned isolation has left him underprepared for Masters

World number 1 Johnson tested positive for Covid-19 last month

Dustin Johnson: 'My health is good. The state of my game is undetermined'. Picture: AP Photo/John Bazemore

World number one Dustin Johnson admits he will be seriously underprepared for next week's Masters after being sidelined due to coronavirus.

Johnson was confined to his hotel room for 11 days after a positive test for Covid-19 last month forced him to miss out on playing the CJ Cup in Las Vegas and the Zozo Championship in California.