Olympic champion Michael Phelps to appear as co-host on live telecast of NBCs 'America's Got Talent'

Phelps, who dominated at Rio Games, holds record 23 Olympic gold medals

Michael Phelps, the most decorated Olympian of all time with 23 gold medals, including five at the just-concluded Rio Games, will appear as a co-host on tonight's live telecast of NBC's "America's Got Talent" (9 p.m. ET/PT).

Phelps has won 28 medals over the course of his Olympic career, which goes back to the 2000 Games in Sydney, Australia, when he was 15. He is a five-time Olympian (2000, 2004, 2008, 2012, 2016), and served as a captain of this year's swim team. He won his first gold medal at the 2004 Olympics in Athens, Greece, and went on to win a total of six during those Games, to begin his medal binge.

During the opening ceremony of the Rio Olympics on Aug. 5, Phelps had the honor of the being the United States flag bearer as the team entered the stadium.

Summer to date, "America's Got Talent" is averaging a 3.2 rating in adults 18-49 and 14.1 million viewers overall with its Tuesday edition, according to "live plus seven day" figures from Nielsen Media Research, to rank as the summer's No. 1 series in both categories. The Tuesday "Talent" is up year-to-year by 7 percent in adult 18-49 rating (3.2 vs. 3.0) and up 13 percent in total viewers (14.1 million vs. 12.5 million), making this its top summer in 18-49 in three years, and best summer in total viewers in five years.

"AGT" has ranked No. 1 among entertainment shows on the broadcast networks every week it's aired so far this summer in both 18-49 and total viewers.

The "America's Got Talent" format was created by Cowell and is co-owned by Syco Entertainment and FremantleMedia. "AGT" holds the Guinness World Record as the most successful reality TV format. The show can be seen in 190 markets worldwide, with more than 500 million global viewers since it began airing in 2006. "Britain's Got Talent" is the U.K.'s highest-rated entertainment show of the century and, in 2009, discovered the global singing sensation Susan Boyle, who has sold 19 million records to date.