Complex sentence: Sampras became the first professional to break Roy Emerson's pre-Open Era record of 12 Grand Slam singles titles and retired with 14 titles (seven Wimbledon, five US Open, two Australian Open), a record since overtaken by Roger Federer and equalled by Rafael Nadal.
Split into simpler sentences: Sampras became the first professional to break Roy Emerson's pre-Open Era record of 12 Grand Slam singles titles. He retired with 14 titles (seven Wimbledon, five US Open, two Australian Open), a record since overtaken by Roger Federer and equalled by Rafael Nadal.