World champs Knierim, Frazier dazzle in Day 1 at nationals

Valentina Plazas and Maximiliano Fernandez compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Alexa Knierim and Brandon Frazier compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Alexa Knierim and Brandon Frazier compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Valentina Plazas and Maximiliano Fernandez compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Alexa Knierim and Brandon Frazier compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Valentina Plazas and Maximiliano Fernandez compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)

Alexa Knierim and Brandon Frazier compete in the pairs short program at the U.S. figure skating championships in San Jose, Calif., Thursday, Jan. 26, 2023. (AP Photo/Godofredo A. Vásquez)