Why does Nadal play tennis left-handed?

At age 8, Nadal won an under-12 regional tennis championship at a time when he was also a promising football player.[10] This made Toni Nadal intensify training, and it was at that time that his uncle encouraged Nadal to play left-handed for a natural advantage on the tennis court, after studying Nadal's then two-handed forehand stroke.[10]

When he was younger, Rafa Nadal used to play with a double handed forehand. His uncle then recommended that he switch to a left-handed stroke in order to have a natural advantage on court.