Out of the top 10, the only ones I could see giving Serena an issue would be Azarenka or Li. Li and her firepower usually gives Serena a challenge despite the H2H. Azarenka can pin Serena behind the baseline and has arguably the best return of serve, but lacks a real weapon to keep Serena guessing.
If Serena can lose twice at majors to players outside the top 20 last year, anything can happen.
"The two-hander is just a more secure ball." - Navratilova
Dunlop 4D 300/M-Fil 400/Aerogel 300. Babolat PS. 2HBH/Cheap Players club's CEO