We have tested a success level of comprehending Ukrainian by different groups of speakers in Estonia: ethnic Russians from Russia who recently have moved to Estonia, local Russians with Russian as L1 and Estonian as L2, simultaneous/early Estonian-Russian bilinguals and speakers of Estonian as L1 with B1 and B2 proficiency in Russian. It was established that all groups of participants were successful in understanding Ukrainian without previous exposure to it. Speakers of Estonian as L1 relied on their knowledge of Russian to understand Ukrainian and were quite succsesful. This mode we called "mediated receptive multilingualism" when understanding is possible via L3 that is closely related to the target. We detected that except for linguistic and material similarity there is a number of extra-linguistic factors that enhance comprehension such as: metalinguistic awareness, exposure to Russian, exposure to various registers, experience with multilingual situations, learnability, and attitudes towards Ukrainian.