The emergence of mega vessels is not a new event in container shipping industry. Containerization has caused a spectacular growth in maritime transportation and brought significant developments to the industry, ranging from operation systems to seaport infrastructure expansion. Container vessels have gotten larger, with some having the capacity of 18,000 TEUs (Triple E Class), to cope with the demand for economies of scale (EOS). Mega vessels can influence the strategic planning of seaport operators for massive infrastructure development and investment on existing terminals at the seaports. The objective ofthis research is to identify and measure the requirements for seaport expansion that need to be prioritized by seaport operators to accommodate mega vessels. Additionally, this research aims to determine the challenges faced by seaport operator to meet the seaport infrastructure expansion requirements. Two mathematical methods were employed, namely Analytical Hierarchy Process (AHP) and Evidential Reasoning (ER). The results showed that the most important requirement for seaport expansion is navigation aspect followed by berth expansion, terminal, yard and gate operations. This research is expected to assist seaport operator in making a decision on prioritizing t requirements for expansion. Furthermore, this research aims to measure the readiness of seaports to serve mega vessels in global shipping industry in order to achieve competitive advantages.