Laker Nation better prepare for the worst ... 'cause NBA super fan Jimmy Goldstein says L.A. has a snowball's chance in hell to beat the Memphis Grizzlies in the first round of the playoffs -- telling TMZ Sports it would be a complete shock if LeBron James and Co. won the series.
Goldstein holds the record for attending the most NBA games in the history of the league ... so naturally, he was present for the Lakers' play-in game against the Minnesota Timberwolves on Tuesday.
Jimmy G says he was thoroughly unimpressed with what he saw from the Purple and Gold in the overtime thriller ... adding it just goes to show they're really not poised to make a deep playoff run this season.
Goldstein points out the Wolves were without defensive stars Rudy Gobert and Jaden McDaniels ... and it wasn't a good sign that the Lake Show needed extra time to put them away.
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He also thinks L.A.'s hot run at the end of the regular season was more due to the fact that their opponents were tanking ... which would explain why they were able to put together some wins.
Long story short -- if you're a betting person, Jimmy thinks you'd be throwing money away to pick the Lakers to win it all.
The Grizzlies vs. Lakers matchup starts on Sunday ... and if Goldstein is right, it won't be a long series.