diff --git a/vaadin-grid-flow-integration-tests/src/main/java/com/vaadin/flow/component/grid/it/GridOnClientAndSlotPage.java b/vaadin-grid-flow-integration-tests/src/main/java/com/vaadin/flow/component/grid/it/GridOnClientAndSlotPage.java
index 1bcbd56e..a468ccf1 100644
--- a/vaadin-grid-flow-integration-tests/src/main/java/com/vaadin/flow/component/grid/it/GridOnClientAndSlotPage.java
+++ b/vaadin-grid-flow-integration-tests/src/main/java/com/vaadin/flow/component/grid/it/GridOnClientAndSlotPage.java
@@ -2,18 +2,27 @@
 
 import com.vaadin.flow.component.grid.Grid;
 import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.component.html.NativeButton;
 import com.vaadin.flow.router.Route;
 
 @Route("grid-on-client-and-slot")
 public class GridOnClientAndSlotPage extends Div {
     public GridOnClientAndSlotPage() {
         GridOnClientAndSlot gridOnClientAndSlot = new GridOnClientAndSlot();
+        
+        gridOnClientAndSlot.add(createGrid());
+        
+        NativeButton addGridButton = new NativeButton("add grid", e -> gridOnClientAndSlot.add(createGrid()));
+        addGridButton.setId("add-new-grid-button");
+
+        add(gridOnClientAndSlot, addGridButton);
+    }
+
+    private Grid<String> createGrid() {
         Grid<String> grid = new Grid<>();
         grid.addColumn(String::toString).setHeader("Column");
         grid.setItems("Item 1", "Item 2", "Item 3", "Item 4");
-        
-        gridOnClientAndSlot.add(grid);
 
-        add(gridOnClientAndSlot);
+        return grid;
     }
 }
diff --git a/vaadin-grid-flow-integration-tests/src/test/java/com/vaadin/flow/component/grid/it/GridOnClientAndServerIT.java b/vaadin-grid-flow-integration-tests/src/test/java/com/vaadin/flow/component/grid/it/GridOnClientAndServerIT.java
index f868702f..b8126b7e 100644
--- a/vaadin-grid-flow-integration-tests/src/test/java/com/vaadin/flow/component/grid/it/GridOnClientAndServerIT.java
+++ b/vaadin-grid-flow-integration-tests/src/test/java/com/vaadin/flow/component/grid/it/GridOnClientAndServerIT.java
@@ -17,6 +17,7 @@
 
 import org.junit.Assert;
 import org.junit.Test;
+import org.openqa.selenium.By;
 
 import com.vaadin.flow.component.grid.testbench.GridTHTDElement;
 import com.vaadin.flow.component.grid.testbench.TreeGridElement;
@@ -34,9 +35,15 @@ public void treeGridOnClientShouldWorkIfAnotherGridIsAddedFromServer() {
     TestBenchElement parent  = $("grid-on-client-and-slot").first();
 
     TreeGridElement treeGrid = parent.$(TreeGridElement.class).id("tree");
-    treeGrid.getExpandToggleElement(0, 0).click();;
+    treeGrid.getExpandToggleElement(0, 0).click();
     GridTHTDElement cell = treeGrid.getCell(1, 0);
 
     Assert.assertEquals("child 1-1", cell.getText().trim());
+
+    findElement(By.id("add-new-grid-button")).click();
+    treeGrid.getExpandToggleElement(3, 0).click();
+    cell = treeGrid.getCell(4, 0);
+
+    Assert.assertEquals("child 2-1", cell.getText().trim());
   }
 }
diff --git a/vaadin-grid-flow/src/main/resources/META-INF/resources/frontend/gridConnector.js b/vaadin-grid-flow/src/main/resources/META-INF/resources/frontend/gridConnector.js
index b3349c12..2c2e619b 100644
--- a/vaadin-grid-flow/src/main/resources/META-INF/resources/frontend/gridConnector.js
+++ b/vaadin-grid-flow/src/main/resources/META-INF/resources/frontend/gridConnector.js
@@ -8,6 +8,8 @@ import { ItemCache } from '@vaadin/vaadin-grid/src/vaadin-grid-data-provider-mix
     return window.Vaadin.Flow.tryCatchWrapper(callback, 'Vaadin Grid', 'vaadin-grid-flow');
   };
 
+  let isItemCacheInitialized = false;
+
   window.Vaadin.Flow.gridConnector = {
     initLazy: grid => tryCatchWrapper(function(grid) {
       // Check whether the connector was already initialized for the grid
@@ -15,60 +17,65 @@ import { ItemCache } from '@vaadin/vaadin-grid/src/vaadin-grid-data-provider-mix
         return;
       }
 
-      // Storing original implementation of the method to be used for client
-      // side only grids
-      ItemCache.prototype.ensureSubCacheForScaledIndexOriginal = ItemCache.prototype.ensureSubCacheForScaledIndex;
-      ItemCache.prototype.ensureSubCacheForScaledIndex = tryCatchWrapper(function(scaledIndex) {
-        if (!this.grid.$connector) {
-          this.ensureSubCacheForScaledIndexOriginal(scaledIndex);
-          return;
-        }
+      // Make sure ItemCache patching is done only once, but delay it for when
+      // a server grid is initialized
+      if (!isItemCacheInitialized) {
+        isItemCacheInitialized = true;
+        // Storing original implementation of the method to be used for client
+        // side only grids
+        ItemCache.prototype.ensureSubCacheForScaledIndexOriginal = ItemCache.prototype.ensureSubCacheForScaledIndex;
+        ItemCache.prototype.ensureSubCacheForScaledIndex = tryCatchWrapper(function(scaledIndex) {
+          if (!this.grid.$connector) {
+            this.ensureSubCacheForScaledIndexOriginal(scaledIndex);
+            return;
+          }
 
-        if (!this.itemCaches[scaledIndex]) {
-          this.grid.$connector.beforeEnsureSubCacheForScaledIndex(this, scaledIndex);
-        }
-      })
+          if (!this.itemCaches[scaledIndex]) {
+            this.grid.$connector.beforeEnsureSubCacheForScaledIndex(this, scaledIndex);
+          }
+        });
 
-      ItemCache.prototype.doEnsureSubCacheForScaledIndex = tryCatchWrapper(function(scaledIndex) {
-        if (!this.itemCaches[scaledIndex]) {
-          const subCache = new ItemCache.prototype.constructor(this.grid, this, this.items[scaledIndex]);
-          subCache.itemkeyCaches = {};
-          if(!this.itemkeyCaches) {
-            this.itemkeyCaches = {};
+        ItemCache.prototype.doEnsureSubCacheForScaledIndex = tryCatchWrapper(function(scaledIndex) {
+          if (!this.itemCaches[scaledIndex]) {
+            const subCache = new ItemCache.prototype.constructor(this.grid, this, this.items[scaledIndex]);
+            subCache.itemkeyCaches = {};
+            if(!this.itemkeyCaches) {
+              this.itemkeyCaches = {};
+            }
+            this.itemCaches[scaledIndex] = subCache;
+            this.itemkeyCaches[this.grid.getItemId(subCache.parentItem)] = subCache;
+            this.grid._loadPage(0, subCache);
           }
-          this.itemCaches[scaledIndex] = subCache;
-          this.itemkeyCaches[this.grid.getItemId(subCache.parentItem)] = subCache;
-          this.grid._loadPage(0, subCache);
-        }
-      })
+        });
 
-      ItemCache.prototype.getCacheAndIndexByKey = tryCatchWrapper(function(key) {
-        for (let index in this.items) {
-          if(grid.getItemId(this.items[index]) === key) {
-            return {cache: this, scaledIndex: index};
+        ItemCache.prototype.getCacheAndIndexByKey = tryCatchWrapper(function(key) {
+          for (let index in this.items) {
+            if(this.grid.getItemId(this.items[index]) === key) {
+              return {cache: this, scaledIndex: index};
+            }
           }
-        }
-        const keys = Object.keys(this.itemkeyCaches);
-        for (let i = 0; i < keys.length; i++) {
-          const expandedKey = keys[i];
-          const subCache = this.itemkeyCaches[expandedKey];
-          let cacheAndIndex = subCache.getCacheAndIndexByKey(key);
-          if(cacheAndIndex) {
-            return cacheAndIndex;
+          const keys = Object.keys(this.itemkeyCaches);
+          for (let i = 0; i < keys.length; i++) {
+            const expandedKey = keys[i];
+            const subCache = this.itemkeyCaches[expandedKey];
+            let cacheAndIndex = subCache.getCacheAndIndexByKey(key);
+            if(cacheAndIndex) {
+              return cacheAndIndex;
+            }
           }
-        }
-        return undefined;
-      })
+          return undefined;
+        });
 
-      ItemCache.prototype.getLevel = tryCatchWrapper(function() {
-        let cache = this;
-        let level = 0;
-        while (cache.parentCache) {
-          cache = cache.parentCache;
-          level++;
-        }
-        return level;
-      })
+        ItemCache.prototype.getLevel = tryCatchWrapper(function() {
+          let cache = this;
+          let level = 0;
+          while (cache.parentCache) {
+            cache = cache.parentCache;
+            level++;
+          }
+          return level;
+        });
+      }
 
       const rootPageCallbacks = {};
       const treePageCallbacks = {};