Defending champion Francesco Molinari has been forced to pull out of the Arnold Palmer Invitational due to a back injury.
The Italian carded a spectacular final round of 64 to come from five shots back and win the tournament last year, finishing two clear of Matt Fitzpatrick.
However, Molinari will not be in action this week after withdrawing ahead of his opening round on Thursday - he had been due to tee off in the morning alongside 2018 Ryder Cup team-mates Rory McIlroy and Justin Rose.
The 37-year-old has not won a tournament on either the European Tour or PGA Tour since his triumph at Bay Hill 12 months ago, admitting ahead of his title defence this week that the season so far had not gone to plan.
"I'm a little bit behind where I was planning to be at this time," Molinari told the media. "The start of the season has not been as good as I hoped for, but it's only the start.
"There's been a few physical things and technical things, but I'm working through it.
"I think I've got some good planning for the next few weeks building up to Augusta and some good direction to work towards."
Lee Kyoung-hoon has taken Molinari's place in a 120-man field that also includes Brooks Koepka, Adam Scott and Patrick Reed.