The 16-year-old eighth seed looked in good form as she earned a hard fought 6-3 7-6 (7-3) victory.
Elsewhere, Tomas Berdych , the No. 7 seed looked in good touch as he dispatched France's Michael Llodra 6-2 6-3 6-3.
CNN: Federer breaks grand slam record as Djokovic marches on
That means the odds of a top seed winning are as good as the other 64 teams combined.
Former Wimbledon champion Martinez is enjoying a good week, having beaten top seed Jennifer Capriati in the previous round.
However, that was as good as it got for the top seed as Henin-Hardenne won the next three games to lead 5-2.
Monte Carlo finalist Guillermo Coria , the 13th seed, kept his recent good form going with a comfortable 6-2 6-2 win over Fernando Verdasco.
Sixth seed Andy Roddick then completed a good night for the Americans by beating Sweden's Thomas Enqvist 6-4 6-4.
Farmers selected plants for seed because they looked and tasted good, without having any idea of what was really different about them.
The incremental process involves finding a good vaccine candidate, reassessing and testing the virus, developing seed vaccines and ensuring their safety.
However, poor farmers frequently cannot afford to buy new seed each season, so they take their chances and replant the best of their seed from year to year in the belief that a new plant that is not quite as good as its parent is better than no plant at all.
ScienceBlogs, the blog network run by privately held Seed Media, which also publishes the eponymous magazine, is one of the best places to find good science writing on the Web.
America, in the 20-odd years since Laury resowed the Schumpeter seed, has added 35 million new jobs--all of them Schumpeter jobs, most of them good paying.
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