Complex sentence: The Rochester Rhinos soccer club played for many years in the A-League, which was the second-highest level American soccer league; the Rhinos even won the U.S. Open Cup against Major League Soccer competition in 1999.
Split into simpler sentences: The Rochester Rhinos soccer club played for many years in the A-League, which was the second-highest level American soccer league. The Rhinos won the U.S. Open Cup against Major League Soccer competition in 1999.