To study the success of an international event handling in Thailand with a focus on the area of mutual communication, this paper aimed to shed light on how English is used as a lingua franca among the local Thai working team and the organizer team who are non-native speakers from different language backgrounds to achieve their mutual understanding and efficaciously execute works in the context of an international golf tournament operation staged in Thailand. Included in the study are lingua franca communication perceptions held by the interlocutors. Additionally, this study explored communication barriers in international interactions, and finally investigated strategies adopted and practiced throughout the event operation period. Using the framework of qualitative analysis research design, this study explored and described how the event working personnel used English as a lingua franca (ELF) to communicate with one another who do not share a first language (L1) background by conducting semi-structured interviews with the 10 participants. The data was then analyzed to see their perceptions, communication barriers and how they overcame non-understanding when there was a breakdown in mutual intelligibility. The findings suggested the organizer team's perceptions towards English communication were positive whereas lack of confidence was found among the local Thai working team when dealing with lingua franca interactions. The lingua franca encounter participants perceived that terminologies used in the working field, limited vocabulary and word choices, grammar points and various accents might disrupt their communication. In order to achieve mutual intelligibility of both parties, the participants applied various communication strategies such as simplifying word choices or sentences, repeating words or statements, cross-checking and using body language. Finally, this case study would give some indications and guidelines for further research in an area of English usage in international business settings, particularly in the Thai context.