Deulofeu, who joined Watford on a permanent deal from Barcelona earlier this summer, has missed training this week with an abdominal problem, which will see him miss the Brighton clash.
"Gerard started to train with the team last week, but he had a little problem," Garcia told reporters. "I think he will be ready in three, four or five days."
The 24-year-old joined Watford on loan from Barcelona in January, and scored once in seven Premier League appearances for the Hornets.
A fractured foot, however, forced the Spaniard to miss seven Premier League matches between the start of March and middle of April.