Arizona Diamondback Jake Lamb got HYPED this weekend ... watching his little bro advance to the College World Series -- and the awesome scene was caught on video.
Washington rallied to beat Cal State Fullerton in 10 innings Sunday night ... using a sacrifice fly to score the winning run -- and Lamb's reaction was priceless.
FYI -- Lamb -- a 3rd baseman on the D'Backs -- used to play for the Huskies ... and now his younger bro, Dylan, is a freshman reliever for the squad. All of that added up to Jake going ballistic when the winning run crossed home plate.