Bad news for every other female tennis player on the planet -- Serena Williams says she will be BACK to destroy all of you ... right after she gives birth! 

Some have speculated the 35-year-old will hang it up after the baby is born -- since there's only 1 other player who's older than her in the Top 75 (it happens to be her sister, Venus). 

But when we saw Serena in NYC, she shot down the retirement talk. 

We also asked if she's having any pregnancy cravings -- and of course, it's healthy.