Rosary continued pushing right up until the final horn in Tuesday night's Class 2A Hampshire sectional semifinal, but couldn't find the back of the net against a steadfast DeKalb squad.
After the Royals held a slight edge in chances and possession during a physical, scoreless first half, DeKalb came out strong after the intermission.
The Barbs finally cashed in 12 minutes into the second half when senior Morgan Beaty turned from 18 yards out and fired a perfectly placed shot into the left corner past the outstretched hands of Rosary standout keeper Lauren Frasca.
Despite a frantic Royals' flurry in the final minutes, DeKalb advanced with a 1-0 victory. The Barbs (14-3-4) will face Rockford Boylan (20-4) in Friday's sectional championship.
"The one mistake of the game -- our whole left side was not in position," Frasca said.
"We knew she's a really good keeper, but she can't cover the entire goal, so we knew anything far post or across the face of the goal was going to be dangerous," said Beaty, who notched her 23rd goal of the season.
Quincy Kellett, Maria Witte, Allyson Sheen, Gabriella Wagoner and Grace Goheen created chances up front for Rosary (10-12-2) in the opening half, but DeKalb keeper Maddie Frye was not seriously tested despite making six saves.
"I thought we were playing really well in the beginning and making nice runs and nice through balls," Kellett said.
"We had more shots and more possession in the first half, but we just couldn't get a quality opportunity on goal," Frasca added.
With a deeper bench, DeKalb wore Rosary down and played a large portion of the second half in Rosary's end.
"Their depth helped out immensely. We were subbing two or three and they were subbing the entire bench," said Rosary coach Brian Frank. "It obviously helped them going forward and it's been something we've been fighting all season."
DeKalb nearly extended the lead with 18:20 left on Alexis Hammond's breakaway, but Frasca thwarted the attempt with a huge kick save to keep the Royals in the game.
"Lauren's an amazing keeper. We're really going to miss her," Kellett said. "She's out there on the field telling everyone where to go."
The Royals put a couple of crosses in the box in the final minute, but failed to generate a potential tying shot on goal.
"We got down by a goal today and they kept fighting, pushing the ball up top, kept creating opportunities," Frank said. "Even in the last minute everybody was up there and it was a mad scramble."