Ishikawa won on the Japan Tour when he was 15-years old.
Ryo Ishikawa might have been more nervous reading a personal invitation from Arnold Palmer than when he won on the Japan Golf Tour at age 15 to become the youngest champion on any recognized tour.
Ishikawa, a 17-year-old sensation who already has risen to No. 60 in the world, has accepted a sponsor's exemption to play in the Arnold Palmer Invitational on March 23-26 at Bay Hill Club in Orlando, Fla.
Palmer, who has a history of recognizing international players before they achieve stardom, wrote to Ishikawa in December.
"I have been following your achievements in Japan and I am quite impressed with what you have accomplished at such a young age," Palmer said in his letter. "I also understand that you have expressed an interest in taking your game to another level by playing some tournaments on the international scene with your eye on the future.
"This leads me to suggest that you might like to come to Florida next March and play in my Arnold Palmer Invitational."
Ishikawa, who won the Mynavi ABC Championship last year and finished fifth on the Japan money list, responded to the letter last week. He will get one of two exemptions that the PGA Tour commissioner reserves for international players.
"When I received your letter, I was so thrilled that my hands became shaky holding your letter," Ishikawa wrote. "I am so honored to play your tournaments with such a great field. Although this is only my second year as a professional golfer and I need to work on a lot of things, it will be a great experience for my career. I will do my best."
Tiger Woods is the defending champion at Bay Hill and could be back on tour by then. Woods has not played since knee surgery a week after winning the U.S. Open in June.
The Arnold Palmer Invitational will not be the PGA Tour debut for Ishikawa. He also is expected to receive a sponsor's exemption to the Northern Trust Open next month at Riviera in Los Angeles, and Nikkansports reported Wednesday that he will play the Transitions Championship at Innisbrook a week before Bay Hill.
Ishikawa made history in 2007 as a 15-year-old freshman in high school by winning the Munsingwear Open KSB Cup, the youngest winner on a tour recognized by the Official World Golf Ranking.
He is known as the "Shy Prince" for his unassuming demeanor, but he already is among the most famous sportsmen in Japan. Along with his first victory as a pro, he was runner-up at the Japan Open and the prestigious Dunlop Phoenix, where past champions include Woods and Padraig Harrington.
Palmer's invitation continues a tradition of spotting young talent and being among the first to invite them to PGA Tour events. Previous Bay Hill exemptions were given to two-time Masters champion Jose Maria Olazabal in 1990, and to a pair of three-time major champions -- Ernie Els of South Africa and Vijay Singh of Fiji -- who were playing the European Tour in 1993.