He returned to the ATP World Tour on 15 February 2016, at Delray Beach, after a long injury-induced absence. Later that year Del Potro gave two of the strongest performances of his career against Andy Murray - in the 2016 Summer Olympics he discovered a huge vein of form, defeating Novak Djokovic in straight sets in the first round and Rafael Nadal in the semifinals, before falling in the final to Andy Murray in an attritional 4 sets. Only weeks later, the two men met again in the Davis Cup semi-final in Glasgow, Del Potro emerging victorious against Murray in 5 sets. He then led Argentina to a first-ever Davis Cup title by defeating Croatia's Marin Čilić in the final in Zagreb. In 2018 he won the Indian Wells Masters singles title after defeating defending champion Roger Federer in the final. He again matched his previous career high of #4 after making the semifinals of the 2018 French Open, and finally reached #3 in August 2018. At the 2018 US Open, he reached his second major final.