The 25-year-old Fowler, who is making his second appearance in the biennial team event this week, raised a few eyebrows when he showed off the letters 'USA' shaved into the side of his head during practice on Monday.
"I thought it was terrific," Watson told a news conference. "It brings a light spirit to the team.
"I wouldn't be surprised if, heck, even Ted Bishop puts 'USA' on the side of his head if it means we are going to win," joked Watson, in reference to the 60-year-old president of the PGA of America.
Europe have won seven of the last nine Ryder Cups and, led by world number one Rory McIlroy, are the favourites to triumph again in the 40th edition at Gleneagles.
Home skipper McGinley broke into a wide grin when he was asked about Fowler's new look.
"That's brilliant," said the Irishman. "I think the guy is so passionate about his country that he will go and do that for the Ryder Cup."
The team competition, the biggest grudge match in golf, gets underway on Friday morning with four fourball encounters.
(Editing by Robert Woodward)
