Sampras's rhymes with:
cypress's, actress's, actresses, choruses, congress', congress's, congresses, cypress's, embarrasses, fortresses, gavras's, heiresses, irises, mattress's, norris's, retroviruses, virus's, waitresses, walruses
Sampras's sounds like:
samberg, samborski, samper's, sampras, sampras', schaumberg, schaumburg, scheinberg, schoenberg, schomberg, schomburg, schonberg, semiprecious, shamburg, sheinberg, sniper's, snipers, snipers', sonnenberg, sonnenburg, swampers, swanberg, szymborski