This study explores the potential of ChatGPT as a virtual tutor to facilitate self-directed learning (SDL) among adult learners in asynchronous online contexts. Although SDL has been identified as a critical skill, factors such as the lack of skills to find resources and the absence of a supportive learning environment could impede adult learners' ability to engage in SDL. By harnessing the power of AI, ChatGPT can assist adult learners in setting learning goals, locating available resources, designing personalized learning plans, monitoring their performance, and reflecting on their learning experiences, ultimately leading to the effective completion of SDL. This study also discusses several existing limitations and challenges, including the need for instructors to provide guidance on creating prompts to use ChatGPT effectively, the possibility of learners becoming reliant on ChatGPT, the significance of institutions to provide policies of proper use of ChatGPT, and the necessary for AI developers to continuously improve the algorithms and data used by the system to minimize the likelihood of providing incorrect and irrelevant information. Additionally, some questions are raised regarding the balance between the use of ChatGPT and engagement with human instructors to ensure optimal learning outcomes. This study aims to enlighten adult educators and practitioners towards the integration of ChatGPT in asynchronous online learning to facilitate adult learning.