The pardon relates to Ali's refusal to report for US military duty in 1967, which would have seen him drafted to fight in the Vietnam War - a conflict that Trump also didn't take part in.
This isn't the first time that these two egos and prominent figures have clashed, so in light of this, let's remember the time that the former world champion eviscerated the current president with a simple statement.
As well as being one of the greatest sports stars of all-time, Ali also possessed one of the one of the sharpest minds, and sharpest tongues, in the game - something that clearly didn't diminish with age, despite his long battle with Parkinson's disease.
At the back end of 2015, as businessman Donald Trump rose to prominence in the US presidential race - with all the Islamophobia that entailed - America's most famous Muslim knocked him down a peg or two in one 132-word statement.
After Trump announced his plan to ban Muslims from entering the US, Ali condemned it and the Republican loud-mouth without even having to mention his name:
I am a Muslim and there is nothing Islamic about killing innocent people in Paris, San Bernardino, or anywhere else in the world. True Muslims know that the ruthless violence of so called Islamic jihadists goes against the very tenets of our religion.
We as Muslims have to stand up to those who use Islam to advance their own personal agenda. They have alienated many from learning about Islam. True Muslims know or should know that it goes against our religion to try and force Islam on anybody.
Speaking as someone who has never been accused of political correctness, I believe that our political leaders should use their position to bring understanding about the religion of Islam and clarify that these misguided murderers have perverted people's views on what Islam really is.
A statement from Muhammad Ali: https://t.co/PO3hZrP7js
While Ali, a three-time world heavyweight champion who converted to Sunni Islam in 1975, did not explicitly refer to Trump, the statement was issued under the headline: 'Presidential Candidates Proposing to Ban Muslim Immigration to the United States’.