Gateway Grizzlies outfielder Brandon Thomas learned a valuable lesson Sunday night after hitting a grand slam:

Power hitters should park far away from the park.

With the local lads lagging 3-0 in the bottom of the second inning, switch-hitting center fielder Thomas smacked a grand slam over the left-field wall of GCS Ballpark in Sauget to put the Grizzlies ahead of the Joliet Slammers, who they eventually beat 17-6.

But score it “E-8” on Thomas for deciding to stash his 2008 Toyota Tundra pickup just beyond the left-field wall — too close for comfort and windshield survival.

“To be honest, I didn’t even think about my truck being out there right after I hit the ball,” Thomas said. “The only thing I was thinking about was whether it would be fair or foul; I knew it was long enough.”

It wasn’t until the next inning that Thomas got the word that he had smashed his own windshield.

That feat now has gotten him scores of media attention and even an interview with ESPN’s “SportsCenter.” But fame was not on Thomas’ mind Sunday night.