We report on p-Λ,p-Λ̄,p̄-Λ, and p̄-Λ̄ correlation functions constructed in central Au-Au collisions at sNN=200 GeV by the STAR experiment at RHIC. The proton and lambda source size is inferred from the p-Λ and p̄-Λ̄ correlation functions. It is found to be smaller than the pion source size also measured by the STAR experiment at smaller transverse masses, in agreement with a scenario of a strong universal collective flow. The p-Λ̄ and p̄-Λ correlation functions, which are measured for the first time, exhibit a large anticorrelat...