Dustin Johnson a doubt for US PGA Championship due to knee problem

The world number one has pulled out of the Byron Nelson Classic

Dustin Johnson is out of this week’s Byron Nelson Classic with a knee injury (Niall Carson/PA)

Dustin Johnson’s participation at this month’s US PGA Championship is in doubt after the world number one withdrew from this week’s Byron Nelson Classic with a knee injury.

Johnson, who had knee surgery in 2019 and endured complications with the injury last year, said he made the decision with “the deepest regret”.