Complex sentence: In the first round, he prevailed against Dominic Thiem in four sets for his first match win in a major championship and as a result, he broke into the top 200 for the first time.
Split into simpler sentences: In the first round, he prevailed against Dominic Thiem in four sets. This was his first win in a major championship and as a result, he broke into the top 200 for the first time.