diff --git a/ui.frontend/src/HTTPAPILayer.js b/ui.frontend/src/HTTPAPILayer.js
index 4fdad424ef..b048f7134a 100644
--- a/ui.frontend/src/HTTPAPILayer.js
+++ b/ui.frontend/src/HTTPAPILayer.js
@@ -66,9 +66,15 @@ class HTTPAPILayer {
             lang = `${params['afAcceptLang']}`
         } else {
             // check for selector in the URL
-            const parts = window.location.pathname.split('.');
-            if (parts?.length >= 3) {
-                lang = `${parts[parts.length - 2]}`;
+            const selectorMatch = (window.location.pathname || "").match(/\/([^/]+)\.html(?=\/|$)/); // capture page name prior to .html
+            if (selectorMatch && selectorMatch.length > 1) {
+                const parts = selectorMatch[1].split('.');
+                if (parts.length >= 2) {
+                    const possibleLocale = parts[parts.length - 1];
+                    if (Constants.LOCALE_SELECTOR_PATTERN.test(possibleLocale)) {
+                        lang = possibleLocale;
+                    }
+                }
             }
         }
         // If 'afAcceptLang' is not set and URL selector is not present, use sites page language
diff --git a/ui.frontend/src/constants.js b/ui.frontend/src/constants.js
index 04d6f8078e..700ecd05ff 100644
--- a/ui.frontend/src/constants.js
+++ b/ui.frontend/src/constants.js
@@ -374,6 +374,12 @@ export const Constants = {
      * @memberof module:FormView~Constants
      * @namespace FIELD_TYPE
      */
-    FIELD_TYPE: FIELD_TYPE
+    FIELD_TYPE: FIELD_TYPE,
+
+    /**
+     * Pattern to detect ISO-like locale selectors (e.g., en, en-US, pt_BR).
+     * @type {RegExp}
+     */
+    LOCALE_SELECTOR_PATTERN: /^[a-z]{2}(?:[-_][a-z0-9]{2,8})?$/i
 };
 
diff --git a/ui.tests/test-module/specs/formContainer/formContainer.runtime.cy.js b/ui.tests/test-module/specs/formContainer/formContainer.runtime.cy.js
index 6ed3961550..f8960ceed0 100644
--- a/ui.tests/test-module/specs/formContainer/formContainer.runtime.cy.js
+++ b/ui.tests/test-module/specs/formContainer/formContainer.runtime.cy.js
@@ -116,3 +116,46 @@ describe("Form Runtime with Hamburger Menu", () => {
 
 })
 
+describe("Form Runtime URL handling", () => {
+    const basePagePath = "content/forms/af/core-components-it/samples/formcontainer/basic.html";
+    const formModelEndpoint = "**/guideContainer.model*.json*";
+
+    const assertFormModelFetch = (formPath) => {
+        cy.intercept("GET", formModelEndpoint).as("fetchFormModelJson");
+        cy.previewForm(formPath).then(container => {
+            expect(container, `formcontainer is initialized`).to.not.be.null;
+            const model = typeof container.getModel === "function" ? container.getModel() : container._model;
+            expect(model, `model is initialized`).to.exist;
+        });
+        cy.wait("@fetchFormModelJson")
+            .its("response.body")
+            .should(body => {
+                expect(body, `response body is available`).to.exist;
+            });
+    };
+
+    it("fetches form model json without locale selector in URL", () => {
+        assertFormModelFetch(basePagePath);
+    });
+
+    it("fetches form model when .fr locale selector is appended", () => {
+        const selectorPath = basePagePath.replace(".html", ".fr.html");
+        assertFormModelFetch(selectorPath);
+    });
+
+    it("fetches form model when .hello.fr selector chain exists", () => {
+        const selectorPath = basePagePath.replace(".html", ".hello.fr.html");
+        assertFormModelFetch(selectorPath);
+    });
+
+    it("fetches form model when DAM asset path is appended", () => {
+        const selectorPath = `${basePagePath}/content/dam/assets/stickers/other/watermark.jpg`;
+        assertFormModelFetch(selectorPath);
+    });
+
+    it("fetches form model when locale selector and asset path exist", () => {
+        const selectorPath = `${basePagePath.replace(".html", ".fr.html")}/content/dam/assets/stickers/other/watermark.jpg`;
+        assertFormModelFetch(selectorPath);
+    });
+});
+