Momiji Nishiya, 13, takes gold in the street skateboarding competition.

Skateboarding is making its Olympic debut at these Games, and Monday was the close of the street discipline, which was contested on a playground of stairs, rails and short ramps meant to simulate something like a schoolyard or an office park. Athletes performed two 45-second runs and five single tricks, and each was judged on a 10-point scale. The four best scores were added together.

There may be an even bigger infusion of youth next week, when skateboarding’s park competition is held with athletes skating in a concrete bowl. In the women’s division, the youngest athletes all have reasonable expectations to win medals.

Kokona Hiraki of Japan is 12 (she will turn 13 a few weeks after the Olympics), but two bigger favorites are Sky Brown of Britain, 13, and Misugu Okamoto of Japan, 15.

The generational shifts were already on full display in street, however, as teenage girls elbowed away the skaters they had long looked to for inspiration.

None may be more of a role model than Bufoni, 28, one of the most famous skaters in the world, who won her sixth X Games gold medal this month in California. She needed a big score on the final trick of her preliminary heat. She landed the trick, but the score fell short of what she needed to reach the final.