Six times, the lead would change hands in the final period, but after Mike Sugamosto's basket put Grimes back in front 58-57 with 2:08 left, the Cobras would not score again, Westhill's defense playing its best in the clutch.
Biles hit the basket with 1:21 left that pushed the Warriors ahead for good, 59-58, with 1:21 to play, and after Stone missed a 3-pointer, McAvoy got open for a lay-up with 42 seconds left to make it 61-58.
Another Grimes possession - and another Stone miss, leading to a fast break and McAvoy connecting on one more basket with 19 seconds left, all but sealing the comeback win.
For the game, Biles had 19 points, 17 of them in the second half, while McAvoy poured in 17 points and junior Joe Meluni had his best game to date, finishing with 14 points. Nigolian added seven points. Four Grimes players hit double figures as Sugamosto led with 15 points, with Stone, Gai Ater and Connor Sohl (12 points each) close behind.
This sets up, for Westhill, the first of two highly-anticipated regular-season clashes with its closest neighbor, Bishop Ludden, on Friday night in Geddes. Ludden is currently in first place in the OHSL Liberty division - but the Warriors, now 4-1 in league play after beating Grimes, could close the gap.