Complex sentence: Despite this run, Djokovic failed to win another title in 2008, not defending his 2007 final appearance at the US Open (lost to Federer), reaching only two tournaments finals in Cincinnati (lost to Murray) and Bangkok (lost to Tsonga).
Split into simpler sentences: Despite this run, Djokovic failed to win another title in 2008. He could not defend his 2007 final appearance at the U.S. Open (lost to Federer), reaching only two tournaments finals in Cincinnati (lost to Murray) and Bangkok (lost to Tsonga).