Katie Couric will be sporting a nasty bruise this holiday season ... revealing she's now black and blue after an unfortunate pickleball accident.

The famed newswoman posted on her Instagram Stories Friday, where she shared an up-close look at the noticeable lump forming on her head.

Per Katie, the large mark -- which appeared to be turning purple -- was caused by a self-inflicted pickleball injury.

She wrote ... "When you hit yourself in the head with the pickleball paddle."

While Katie was clearly trying to laugh off the unfortunate injury, she did appear a bit embarrassed by it all ... she had a distinct grimace on her face as she held an icepack to her forehead in another pic from her pickleball game.

Her friends, who the former "Today" personality called her "queens," seemed to get a good laugh from the situation ... as they smiled wide in one update from the pickleball court.

Katie is just the latest celebrity who has jumped on the pickleball trend -- which just so happens to be the fastest-growing sport in the United States.

She's joined the likes of Taylor Swift, Dax Shepard, Katy Perry, Ellen DeGeneres and Michael Phelps, among others.

Here's hoping Katie's unfortunate accident doesn't keep her from the court for too long.