Why is the sports world angry at Donald Trump?

Addressing a rally in Alabama, Trump said that NFL players who refused to stand up during the national anthem should be fired by their teams.

In Trump's own words, team managers should say, "Get that son of a bitch off the field right now, he's fired."

"If fans leave the stadium when the players protest... I guarantee this would stop," he added.

Following on Kaepernick's footsteps, major league baseball player Bruce Maxwell of "Oakland Athletics" kneeled during the national anthem in protest.

"The President's comments are contradictory to what this great country stands for," stated Jed York, CEO of NFL team San Francisco 49ers.

NFL players Association lashed out at Trump stating that the President was effectively telling them to "shut up and play."

Trump withdrew an invitation to Golden State Warriors who won the NBA, in response to star-player, Stephen Curry's statement that he didn't want to visit the White House.

Amid the NFL row, this has significantly annoyed other NBA players.

LeBron James, triple NBA champion termed Trump a "bum."

"Going to White House was an honor until you showed up," tweeted the legendary Kobe Bryant.

Trump invited liberal outrage when he chose to not condemn white supremacists at a rally in Texas after the recent Charlottesville attack.

Trump seems to be sparking similar rows as he knows these would bring his supporters closer. He could just be playing smart politics.

According to BBC's Anthony Zurcher, "Trump knows his audience and he knows how to change the subject."