The Bishop Macdonell Celtics upset the first-place Centre Wellington Falcons 1-0 on the road Monday to reach the District 10 field hockey finals.
Centre Wellington finished first in regular season play with a 6-1-0 record, scoring 40 goals and conceding just two.
Bishop Mac was in fifth this season with a 3-4-0 mark, scoring 23 goals and allowing eight.
Scoring details were not available.
In the other semifinal game Monday, the third-place Centennial Spartans topped second-place Orangeville, 3-0 in penalty flicks on the road.
Details were not made available.
The Bishop Mac-Centennial championship game takes place Wednesday at the University of Guelph at 2:30 p.m.