diff --git a/spec/suites/layer/tile/GridLayerSpec.js b/spec/suites/layer/tile/GridLayerSpec.js
index c8e8e243..273c50f1 100644
--- a/spec/suites/layer/tile/GridLayerSpec.js
+++ b/spec/suites/layer/tile/GridLayerSpec.js
@@ -599,46 +599,84 @@ describe('GridLayer', function () {
 		// browsers due to CSS animations!
 		it.skipInPhantom("Loads 32, unloads 16 tiles zooming in 10-11", function (done) {
 
-			// grid.on('tileload tileunload tileloadstart load', logTiles);
+			// Advance the time to !== 0 otherwise `tile.loaded` timestamp will appear to be falsy.
+			clock.tick(1);
+			// Date.now() is 1.
 
-			grid.on('load', function () {
-				expect(counts.tileloadstart).to.be(16);
+			// grid.on('tileload tileunload tileloadstart load loading', logTiles);
+
+			// Use "once" to automatically detach the listener,
+			// and avoid removing the above logTiles
+			// (which would happen when calling "grid.off('load')").
+			grid.once('load', function () {
 				expect(counts.tileload).to.be(16);
 				expect(counts.tileunload).to.be(0);
-				grid.off('load');
-
-				// grid.on('load', logTiles);
-				grid.on('load', function () {
-
-					// We're one frame into the zoom animation, there are
-					// 16 tiles for z10 plus 16 tiles for z11 covering the
-					// bounds at the *end* of the zoom-*in* anim
-					expect(counts.tileloadstart).to.be(32);
-					expect(counts.tileload).to.be(32);
-					expect(counts.tileunload).to.be(0);
 
+				// Wait for a frame to let _updateOpacity starting.
+				L.Util.requestAnimFrame(function () {
 					// Wait > 250msec for the tile fade-in animation to complete,
 					// which triggers the tile pruning
 					clock.tick(300);
+					// At 251ms, the pruneTile from the end of the z10 tiles fade-in animation executes.
+					// Date.now() is 301.
 
-					// After the zoom-in, the 'outside' 12 tiles (not the 4
-					// at the center, still in bounds) have been unloaded.
-					expect(counts.tileunload).to.be(12);
-
-					L.Util.requestAnimFrame(function () {
-						expect(counts.tileloadstart).to.be(32);
+					grid.once('load', function () {
 						expect(counts.tileload).to.be(32);
-						expect(counts.tileunload).to.be(16);
-						done();
-					});
-				});
 
-				map.setZoom(11, {animate: true});
-				clock.tick(250);
+						// We're one frame into the zoom animation,
+						// so GridLayer._setView with noPrune === undefined is not called yet
+						// No tile should be unloaded yet.
+						expect(counts.tileunload).to.be(0);
+
+						// Wait > 250msec for the zoom animation to complete,
+						// which triggers the tile pruning
+						// Animated zoom takes 1 frame + 250ms before firing "zoom" event
+						// => GridLayer._resetView => GridLayer._setView => _pruneTiles
+						// However, this "load" event callback executes synchronously,
+						// i.e. _tileReady still did not have a chance to prepare the
+						// setTimeout(250) for pruning after the end of the fade-in animation.
+						clock.tick(300);
+						// At 301 + 250 = 551ms, the pruneTile from the end of the zoom animation executes.
+						// It unloads the 'outside' 12 tiles from z10, but not the 4 tiles in the center,
+						// since _updateOpacity did not have a chance yet to flag the 16 new z11 tiles as "active".
+						expect(counts.tileunload).to.be(12);
+						// Date.now() is 601.
+
+						// Wait for a frame to let _updateOpacity starting
+						// + _tileReady to be able to prepare its setTimeout(250)
+						// for pruning after the end of the fade-in animation.
+						// Since we are already > 200ms since the 'load' event fired,
+						// _updateOpacity should directly set the current tiles as "active",
+						// so the remaining 4 tiles from z10 can then be pruned.
+						// However we have skipped any pruning from _updateOpacity,
+						// so we will have to rely on the setTimeout from _tileReady.
+						L.Util.requestAnimFrame(function () {
+							// Wait > 250msec for the tile fade-in animation to complete,
+							// which triggers the tile pruning
+							clock.tick(300);
+							// At 851ms, the pruneTile from the end of the z11 tiles fade-in animation executes.
+							// It unloads the remaining 4 tiles from z10.
+							expect(counts.tileunload).to.be(16);
+							// Date.now() is 901.
+							done();
+						});
+					});
+
+					map.setZoom(11, {animate: true});
+					// Animation (and new tiles loading) starts after 1 frame.
+					L.Util.requestAnimFrame(function () {
+						// 16 extra tiles from z11 being loaded. Total 16 + 16 = 32.
+						expect(counts.tileloadstart).to.be(32);
+					});
+
+				});
 			});
 
 			map.addLayer(grid).setView([0, 0], 10);
-			clock.tick(250);
+			// The first setView does not animated, therefore it starts loading tiles immediately.
+			// 16 tiles from z10 being loaded.
+			expect(counts.tileloadstart).to.be(16);
+			// At 1ms, first pruneTile (map fires "viewreset" event => GridLayer._resetView => GridLayer._setView => _pruneTiles).
 		});
 
 		it("Loads 32, unloads 16 tiles zooming in 10-18", function (done) {