Complex sentence: He became a Grand Slam singles champion when he won the title at the 2003 US Open, defeating Juan Carlos Ferrero in the final, which currently makes him the last North American male player to win a Grand Slam singles event.
Split into simpler sentences: He became a Grand Slam singles champion when he won the title at the 2003 US Open, defeating Juan Carlos Ferrero in the final. He is currently the last North American male player to win a Grand Slam singles event.