Ingebrigtsen, who had won the 3,000m on Saturday for his first world indoor title, clocked 3min 38.79sec to emulate the double claimed by Ethiopian legend Haile Gebrselassie in Maebashi in 1999.
Britain’s Neil Gourley took silver in 3:39.07 while American Luke Houser rounded out the podium (3:39.17).
“Of course this is something special,” said Ingebrigtsen, before adding: “A lot of things have changed and I’m not doing this because anyone else has done it before. So that’s purely a coincidence.
“It’s very difficult to compare yourself against history and what others are doing.
“I’m only focusing on myself and I feel good to have done a lot of preparations, and that was always the main goal. It’s not to do with something somebody else did before.
“I think I can do more, so I’ll try to maximise that and grab the opportunity given to me.”
Ingebrigtsen’s victory also banished some of the Norwegian’s 1,500m demons.
“The main goal is obviously to win both distances, but I would say so far a pretty good indoor season, getting out and succeeding with the things that I wanted to accomplish, so it’s been good,” he said.
Ingebrigtsen, as his wont, was happy to sit at the back of the nine-strong pack as American Samuel Prakel took up the running in Nanjing, splitting the pack into single file.
The Norwegian moved to the front with four laps to run, Britain’s Gourley on his shoulder and Mariano Garcia of Spain also in the running.
Ingebrigtsen surged again, shouldering off Austrian veteran Raphael Pallitsch’s clumsy attempt at a pass.
Next to try their luck was Portugal’s Isaac Nader, but at the bell it was Ingebrigtsen in charge.
Gourley raced down the inside line of the far straight, but there was to be no Briton to spoil the party at the line, as there has been twice at the world outdoors.
The Norwegian kept not only his speed but also his nerve to see off his rivals, crossing the finish line with a brief look over his shoulder and a wagging index finger. (AFP)
