Complex sentence: Due to a left forearm injury sustained at the start of the year, Sharapova withdrew from the Qatar Open, and a week before the BNP Paribas Open, she withdrew from that for the same reason.
Split into simpler sentences: Due to a left forearm injury sustained at the start of the year, Sharapova withdrew from the Qatar Open. A week before the BNP Paribas Open, Sharapova withdrew due to the same reason.