On January 26, 2013, at the indoor Terrier Classic at Boston University, Rupp made an attempt to break the American indoor mile record, where he won the mile in 3:50.92, the fifth-fastest indoor mile ever run, in a field that included four other sub-four-minute performers. Rupp's time was behind only that of Bernard Lagat among Americans. Rupp was second at the Boston Indoor Grand Prix 3000 m. On February 21, 2013, Rupp broke Lagat's national indoor record at 3000 m by more than two seconds with a time of 7:30.16 at the XL Galan meet in Stockholm, Sweden.