diff --git a/packages/main/src/Popover.ts b/packages/main/src/Popover.ts
index 70eca0db7b5b..39d74d52d9bd 100644
--- a/packages/main/src/Popover.ts
+++ b/packages/main/src/Popover.ts
@@ -301,13 +301,13 @@ class Popover extends Popup {
 			return opener;
 		}
 
-		const rootNode = this.getRootNode();
+		let rootNode = this.getRootNode();
 
-		if (!(rootNode instanceof ShadowRoot || rootNode instanceof Document)) {
-			return;
+		if (rootNode === this) {
+			rootNode = document;
 		}
 
-		let openerHTMLElement = rootNode.getElementById(opener);
+		let openerHTMLElement = (rootNode as Document | ShadowRoot).getElementById(opener);
 
 		if (rootNode instanceof ShadowRoot && !openerHTMLElement) {
 			openerHTMLElement = document.getElementById(opener);
diff --git a/packages/main/test/pages/PopoverInitiallyOpen.html b/packages/main/test/pages/PopoverInitiallyOpen.html
index 85b8ab8ae68b..1b1a31b4ed54 100644
--- a/packages/main/test/pages/PopoverInitiallyOpen.html
+++ b/packages/main/test/pages/PopoverInitiallyOpen.html
@@ -5,7 +5,7 @@
 	<meta charset="utf-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
 
-	<title>Dialog</title>
+	<title>Popover Initially Open</title>
 
 	<script data-ui5-config type="application/json">
 		{
@@ -16,14 +16,14 @@
 	<script>
 		function init() {
 			const popover = document.createElement("ui5-popover");
-			popover.id = "dialogOpen";
-			popover.headerText = "Dialog Header";
+			popover.id = "popoverOpen";
+			popover.headerText = "Popover Header";
 
 			popover.open = true;
 			popover.opener = "btn1";
 
 			const content = document.createElement("div");
-			content.innerHTML = "<button>button</button>";
+			content.innerHTML = "<button id='popoverBtn'>button</button>";
 			popover.appendChild(content);
 
 			document.body.appendChild(popover);
diff --git a/packages/main/test/specs/Popover.spec.js b/packages/main/test/specs/Popover.spec.js
index e21ff3b8a777..8e54a905c3ed 100644
--- a/packages/main/test/specs/Popover.spec.js
+++ b/packages/main/test/specs/Popover.spec.js
@@ -463,6 +463,20 @@ describe("Opener", () => {
 	});
 });
 
+describe("Initially opened", () => {
+	before(async () => {
+		await browser.url(`test/pages/PopoverInitiallyOpen.html`);
+	});
+
+	it("test :popover-open selector", async () => {
+		assert.ok(await browser.$("#popoverOpen").matches(":popover-open"), "popover is opened correctly");
+	});
+
+	it("test initial focus", async () => {
+		assert.ok(await browser.$("#popoverBtn").matches(":focus"), "initial focus is correct");
+	});
+});
+
 describe("Acc", () => {
 	before(async () => {
 		await browser.url(`test/pages/Popover.html`);