Serena Williams is making an adjustment -- to her real estate game -- by slashing the price of her Bel-Air home ... to just a shade under $10 million.
The tennis star put the 6,101 sq ft, 6-bed, 7-bath mansion -- featuring a pool, gym, bar, salon and private hiking trails -- on the market for $12 mil back in October ... but apparently hasn't had any takers.
With a new price tag of $9,995,000, Serena's still set to make a nice profit on the sale -- she bought the place for just over $6 mil in 2006.
As we reported ... Serena plunked down $6.7 mil on a Beverly Hills pad right around the same time she listed her Bel-Air palace with Greg Piechota from KASE Real Estate.
So ... don't worry about her not having a place to stay in L.A.