Billy Demong of Park City, Utah, the defending gold medalist on the large hill, was the leading American, finishing 24th overall. He finished 31st in ski jumping, started 1:33 after Frenzel and was 1:49.6 behind at the end.
Bryan Fletcher of Steamboat Springs, Colo., was 41st after jumping, gave Frenzel a 1:44 head start and finished 26th, 1:55.5 behind.
Fletcher's brother Taylor was last in the jumping portion, started 2:34 behind and finished 33rd, 2:32.7 behind, making up two seconds on the cross-country leg.
Todd Lodwick, also from Steamboat Springs, finished 34th in the jumping and said later he would not compete in the cross-country portion. Lodwick, 37, who is attending his sixth Winter Games, has an injured shoulder and wants to save himself for the Feb. 20 team competition, where the U.S. won silver in Vancouver in 2010.
The 25-year-old Frenzel, who has served in the German army, has been the most consistent Nordic combined athlete in the last two years. He leads this season's championship by 352 points after winning seven of the 11 events he has entered. He now has a gold medal to go with the Olympic bronze he won with the German team on the large hill at Vancouver in 2010.
Two hours earlier, Frenzel, jumping last, soared 103 meters and scored 131.5 points to overcome the 100.5 meters and 130.0 points posted by Watabe immediately before him. That ensured the German was first off in the cross-country event on the 2.5-kilometer loop course adjacent to the ski jump.
The next Nordic combined gold medal — the individual large hill — will be contested on Feb. 18. The men's team event two days later will be the final Olympic competition at the RusSki Gorki Jumping Center.