LYTHAM ST. ANNES, England — South African teenager Aldrich Potgieter built an enormous lead over 18 holes and withstood a big rally by Sam Bairstow to win the British Amateur on Saturday at Royal Lytham & St. Annes and secure his spot in three majors.

Potgieter had a 4-under 66 in the morning round to take a 7-up lead over Bairstow, only for the English golfer to claw his way back into the mix. Potgieter's lead was down to two holes with four to play when Bairstow took a double bogey on the 15th that ended his hopes.

The 17-year-old South African closed it out with a par on the 16th.

“On this golf course, going bogey free on the first 18 holes was incredible for me. I played really well and everything worked out well," Potgieter said. "I knew Sam was going to do better than he did this morning. He wasn’t going to give up. I just had to play steady and keep my lead.”

Potgieter became the youngest British Amateur champion since 16-year-old Matteo Manassero in 2009 and the third South African winner in 127 years of the championship.

The victory gets him into the British Open next month, along with the Masters and the U.S. Open next year.