PHILADELPHIA - President Donald Trump mixed politics and sports Saturday, announcing the departure of his chief of staff before settling in for Army-Navy football game.

The commander in chief flew to Philadelphia for the 119th meeting in the storied rivalry between the service academies and officiated the coin toss at Lincoln Financial Field, home of the Super Bowl champion Philadelphia Eagles. Navy called "tails," and that's what it was when Trump's flipped coin landed on the turf. Navy elected to kick off.

As he left the White House, Trump told reporters that chief of staff John Kelly would step down at year's end. The president was expected to soon name a replacement, and a White House official said Nick Ayers, Vice President Mike Pence's chief of staff, was Trump's top choice.

Earlier Saturday, Trump picked an Army general, Mark Milley, to be his next top military adviser.

Trump, who saw the Army-Navy contest in 2016 as president-elect, is the 10th sitting president to go to the game. President Theodore Roosevelt was the first, in 1901.

Like previous commanders in chief, Trump was expected to switch sides at halftime in a show of impartiality.

No. 22 Army (9-2) is in the AP Top 25 for the first time since 1996. The Black Knights have won seven in a row and have defeated Navy (3-9) two straight years.

The series began in 1890, and Navy leads 60-51-7.