Complex sentence: His first major success came when he won the 1993 UK Championship at the age of 17 years and 358 days, making him the youngest player ever to win a professional ranking tournament, a record he still holds.
Split into simpler sentences: His first major success came when he won the 1993 UK Championship at the age of 17 years and 358 days. This made him the youngest player ever to win a professional ranking tournament, a record he still holds.