John Legend was all smiles with his kids after the exhilarating World Series game 1 ending ... and Chrissy Teigen took a moment to give him a fun jab for his apparent lack of baseball knowledge.

Here's the deal ... the Dodgers defeated the Yankees thanks to a history-making walk-off grand slam ... belted by Freddie Freeman in the bottom of the 10th inning.

John celebrated the moment with his kids and posted the snap to Instagram ... "Wow. One of the craziest live sports moments I’ve seen. Walk off grand slam in the bottom of the 10th. Great World Series Game 1!"

It didn't take long for Chrissy to bust his chops ... commenting ... "you didn’t even know it was a grand slam til I said it was, don’t make me post the receipts."

So far ... the sassy comment has over 3,000 likes -- which means it's the first thing users see on his post.

JL was among a slew of stars who turned out to support the Dodgers ... which included Jason Bateman, Jimmy Kimmel, Bryan Cranston, Lil Wayne, Billie Eilish and Finneas, Pat Sajak, and many more as fans came to watch the Dodgers beat the Yankees 6-3.