But then "The Star-Spangled Banner", the USA national anthem, began to play and everyone stood up to put their hands on their chests and sing the lyrics proudly, and it looked very much as through the President could not remember all the lyrics of the song.
"Trump being down on the field, walking out with the troops, singing along with the National Anthem with such pride, is the very definition of Pro-America".
On the way to the game on Monday, Trump signed a law creating a new national historic park for the Rev. Martin Luther King Jr.
There was no such kneeling protest before the game as college players remained in their locker rooms during the anthem.
However, what caught the world's attention was how the president miserably failed at singing the National Anthem.
But while Trump himself has added fire to this issue, there are legitimate reasons why the president may not have sung the entire anthem.
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But supporters praised the president for taking the field, hand on heart.
Check out a few more reactions here.
Former President Ronald Reagan once said: "I can't claim to know the words of all the national anthems in the world, but I don't know of any other that ends with a question and a challenge as ours does".
Trump is believed to have left the game after the first half, thereby missing the half-time entertainment from rapper Kendrick Lamar, who is no fan of the president.
The Flag Code covers aspects of etiquette when the anthem is played in some detail.
The president appeared to sing part of the anthem with his hand held over his heart. In October 2017, he had also asked Vice President Mike Pence to leave an Indianapolis Colts game early after the players knelt during the National Anthem. The league's commissioner, Roger Goodell, responded in a statement at the time, saying, "Divisive comments like these demonstrate an unfortunate lack of respect for the NFL, our great game and all of our players".