Complex sentence: Sawamatsu retired from professional tennis after losing in the second round of the 1998 Japan Open to Monica Seles in a three set match 6--3,3--6,6--3.
Split into simpler sentences: Sawamatsu retired from professional tennis after her loss in the second round of the Japan Open in 1998. Her last match was a loss to Monica Seles 6--3,3--6,6--3.