Phased radiofrequency ablation with a single catheter technique, using a 9-electrode circumferential catheter, is a viable approach to pulmonary vein isolation for the treatment of atrial fibrillation. However, creating effective transmural lesions with such technique, while avoiding serious complications like atrioesophageal fistula, can be difficult. This case illustrates a challenging scenario, where catheter maneuvers fail to allow safe radiofrequency delivery, due to esophageal temperature rise, despite extensive navigating maneuvers. Changing the bipolar-to-unipolar ratio of energy delivery, from 2:1 to 4:1, allowed the creation of effective lesions, avoiding excessive increase in esophageal temperature.