diff --git a/js/components/WarningPopup.js b/js/components/WarningPopup.js
new file mode 100644
index 0000000..a1196cc
--- /dev/null
+++ b/js/components/WarningPopup.js
@@ -0,0 +1,23 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import {Alert} from 'reactstrap';
+
+export class WarningPopup extends React.Component {
+    render() {
+        if (this.props.shown) {
+            return (<div>
+                {this.props.children}
+                <Alert className="mt-2" color="danger">
+                    {this.props.text}
+                </Alert>
+            </div>);
+        } else {
+            return this.props.children;
+        }
+    }
+}
+
+WarningPopup.propTypes = {
+    text: PropTypes.string.isRequired,
+    shown: PropTypes.bool.isRequired
+}
\ No newline at end of file
diff --git a/pages/create.js b/pages/create.js
index 1a81f1f..acbedb8 100644
--- a/pages/create.js
+++ b/pages/create.js
@@ -8,6 +8,7 @@ import {TurniereNavigation} from '../js/components/Navigation';
 import {Footer} from '../js/components/Footer';
 import EditableStringList from '../js/components/EditableStringList';
 import {createTournament} from '../js/api';
+import {WarningPopup} from '../js/components/WarningPopup'
 
 import '../static/css/everypage.css';
 import RequireLogin from '../js/components/RequireLogin';
@@ -50,7 +51,7 @@ function CreateTournamentCard() {
 
 const GroupphaseFader = posed.div({
     visible: {
-        opacity: 1, height: 150
+        opacity: 1, height: 200
     }, hidden: {
         opacity: 0, height: 0
     }
@@ -118,11 +119,14 @@ class CreateTournamentForm extends React.Component {
                     <FormGroup>
                         <Label for="teams-group-to-playoff">Wie viele Teams sollen nach der Gruppenphase
                             weiterkommen?</Label>
-                        <Col xs="3" className="pl-0">
-                            <NumericInput value={this.state.groupAdvance}
-                                incrementText="&#215;2" incrementCallback={this.increaseGroupAdvance}
-                                decrementText="&#247;2" decrementCallback={this.decreaseGroupAdvance}/>
-                        </Col>
+                        <WarningPopup text="Füge bitte noch Teams hinzu, um so viele Teams im Playoff zu haben."
+                            shown={this.state.teams.length < this.state.groupAdvance}>
+                            <Col xs="3" className="pl-0">
+                                <NumericInput value={this.state.groupAdvance}
+                                    incrementText="&#215;2" incrementCallback={this.increaseGroupAdvance}
+                                    decrementText="&#247;2" decrementCallback={this.decreaseGroupAdvance}/>
+                            </Col>
+                        </WarningPopup>
                     </FormGroup>
                 </GroupphaseFader>
             </Form>
@@ -204,11 +208,13 @@ class CreateTournamentForm extends React.Component {
             }, () => {
                 notify.show('Das Turnier konnte nicht erstellt werden.', 'warning', 5000);
             });
+        } else {
+            notify.show('Bitte korrigiere deine Eingaben zuerst.', 'warning', 5000);
         }
     }
 
     valuesAreCredible() {
-        return this.state.groups.length >= this.state.groupAdvance;
+        return this.state.teams.length >= this.state.groupAdvance;
     }
 
     generateTournamentCreationObject() {