Complex sentence: Guan qualified for the 2013 Masters tournament by winning the 2012 Asia-Pacific Amateur Championship in Thailand, and subsequently became the youngest player ever to qualify for the tournament, beating previous record holder Matteo Manassero.
Split into simpler sentences: Guan qualified for the 2013 Masters tournament by winning the 2012 Asia-Pacific Amateur Championship. He is the youngest player ever to qualify for the tournament, beating previous record holder Matteo Manassero.