"That four run inning was a big one," said CU coach Woody Hunt.
"Grinstead is a very good hitter, Union deserved it today. I give credit to them.
"We’ve got tomorrow, and I guess that’s the way it should be. Two good teams, both battling hard to get to the World Series.
"We know we’ve got to win to get to Lewiston. We’ve got to come out, focus on the game and see what happens. If it happens for us, it happens. If it doesn’t, life goes on."
CU (46-20) took a 1-0 lead in the third as James Lilley drove in Austin Morgan from third after a nice sac bunt by Will Curry.
Union answered with a run in the top of the fourth as David Fairbanks pushed a perfect bunt toward second base, scoring Josh Ehringer from third.
Bulldog outfielder Jason Bush led off the bottom of the fourth with his eighth homer of the season. Later in the frame, Curry dumped a Texas-leaguer over first to drive in Tyler Fisher, who had reached on a single.
Cumberland loaded the bases with two out in the bottom of the eighth, but Union ace Marty Popham retired Brian Lucas swinging to retire the side.
Popham, who leads in the NAIA in wins, improved to 16-1 on the season. Hewent the full nine innings, scattering nine hits with six strikeouts and five walks.
Grinstead pounded out three hits while the bottom of the Union lineup, Brett McAlpin and David Fairbanks, rapped out two hits apiece and each drove in a run.
Bush led Cumberland with a 3-for-4 day at the plate while six other players finished with one hit each.
CU starter Eric Spivey (5-5) went 6.2 innings, allowed 14 hits and four earned runs to take the loss.
Union, the NAIA Region XII champion, is trying to earn the program’s first trip to the NAIA World Series.Cumberland, the five-time defending Region XII champ, is looking for its 11th World Series appearance, and fifth consecutive.