Drawing on a case study design, this article examines the real-life adaptive challenges secondary school teachers of English in Uganda face while implementing the 2020 English language competence-based curriculum innovation. Findings indicate that scarcity of instructional materials, time constraints and large class sizes, limited planning and stakeholders' support, dissonance between local culture and learning styles significantly underlie complications ESL teachers face adapting and implementing competence-based curricula innovations in English language classrooms in low-income contexts in the global south. The experiences of teachers in Uganda resonate across most global south ESL educational contexts. They illustrate the universality of challenges teachers face and are likely to face when implementing competence-based curricula in sub-Saharan Africa and the wider global south where the teaching and learning of English is premised on facilitating acquisition of English language for meaningful interaction.