Jake Chaffetz scored a goal from nearly midfield as the Tigers topped Fruita Monument, 1-0.
With the win Grand Junction earned the three-game season sweep of the Wildcats.
The Tigers improve to 11-1 on the year and 5-0 in league play.
Fruita drops to below .500 at 6-7 and 1-5 in the Southwestern League.
Fruita will finish the season at home against Montrose on October 19.
Grand Junction will finish the regular season with three straight road games starting with Durango on Saturday.