Oslo Opera House debuts as a sports venue as the Red Bull Cliff Diving elite showcase their skills from the rooftop. On a competitive afternoon in Norway’s capital city, Romania’s Constantin Popovici narrowly defeated compatriot Catalin Preda to victory in what turned out to be more of a “Romanian rumble” than an exhibition at the Oslo Opera House. Following a slow start in Friday’s first round, Preda roared into life on Saturday afternoon, displaying the same acrobatic finesse and unerring precision that fired him to victory at the first stop of the Red Bull Cliff Diving World Series in Saint-Raphaël in June. “Yesterday the weather surprised me and I’m really happy with how I recovered myself today,” Preda said. “That’s certainly a confidence booster!” Popovici was in equally stunning form, ripping the final dive of the competition under pressure to edge past his rival. “It was a competition between Catalin, …