The book on Serena Williams' career ain't closed yet ... the tennis legend moved on in the U.S. Open on Wednesday night with a huge win -- and Tiger Woods was there to cheer it all on!!
Williams upset No. 2 seed Anett Kontaveit, 7-6 (4), 2-6, 6-2, in New York -- dominating for most of the match.
The 40-year-old looked to be in vintage form, despite only playing a handful of times prior to the major tournament this year.