diff --git a/src/components/TournamentForm/TournamentForm.schema.ts b/src/components/TournamentForm/TournamentForm.schema.ts
index 53584fbf..0848dd9f 100644
--- a/src/components/TournamentForm/TournamentForm.schema.ts
+++ b/src/components/TournamentForm/TournamentForm.schema.ts
@@ -1,4 +1,3 @@
-import { zodResolver } from '@hookform/resolvers/zod';
 import {
   CurrencyCode,
   GameSystem,
@@ -15,8 +14,12 @@ import {
   validateGameSystemConfig,
 } from '~/components/GameSystemConfigFields';
 
+interface CreateSchemaConfig {
+  competitorCount: number;
+}
+
 // TODO: Convert gameSystemConfig to union of other game systems
-export const tournamentFormSchema = z.object({
+export const createSchema = (config: CreateSchemaConfig) => z.object({
 
   // General
   title: z.string().min(3, 'Title must be at least 3 characters.').max(40, 'Titles are limited to 40 characters.'),
@@ -97,15 +100,20 @@ export const tournamentFormSchema = z.object({
       path: ['pairingConfig'],
     });
   }
+  if (data.maxCompetitors < config.competitorCount) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: `Can not set tournament size to ${data.maxCompetitors} when there are already ${config.competitorCount} ${data.competitorSize > 1 ? 'teams' : 'players'} registered.`,
+      path: ['maxCompetitors'],
+    });
+  }
 });
 
-export const tournamentFormResolver = zodResolver(tournamentFormSchema);
-
 export type TournamentSubmitData = TournamentEditableFields;
 
-export type TournamentFormData = z.infer<typeof tournamentFormSchema>;
+export type TournamentFormData = z.infer<ReturnType<typeof createSchema>>;
 
-export const defaultValues: Omit<z.infer<typeof tournamentFormSchema>, 'location'> = {
+export const defaultValues: Omit<z.infer<ReturnType<typeof createSchema>>, 'location'> = {
   maxCompetitors: 20,
   competitorSize: 1,
   useNationalTeams: false,
diff --git a/src/components/TournamentForm/TournamentForm.tsx b/src/components/TournamentForm/TournamentForm.tsx
index 0fcc9605..a6ec10ad 100644
--- a/src/components/TournamentForm/TournamentForm.tsx
+++ b/src/components/TournamentForm/TournamentForm.tsx
@@ -12,6 +12,7 @@ import { GameSystemConfigFields } from '~/components/GameSystemConfigFields';
 import { Card } from '~/components/generic/Card';
 import { Form, FormField } from '~/components/generic/Form';
 import { InputSelect } from '~/components/generic/InputSelect';
+import { useGetTournamentCompetitorsByTournament } from '~/services/tournamentCompetitors';
 import { useGetTournament } from '~/services/tournaments';
 import { validateForm } from '~/utils/validateForm';
 import { CompetitorFields } from './components/CompetitorFields';
@@ -19,9 +20,9 @@ import { FormatFields } from './components/FormatFields';
 import { GeneralFields } from './components/GeneralFields';
 import { PairingFields } from './components/PairingFields';
 import {
+  createSchema,
   defaultValues,
   TournamentFormData,
-  tournamentFormSchema,
   TournamentSubmitData,
 } from './TournamentForm.schema';
 import { convertDateToEpoch, convertEpochToDate } from './TournamentForm.utils';
@@ -41,7 +42,12 @@ export const TournamentForm = ({
   onSubmit: handleSubmit,
   tournamentId,
 }: TournamentFormProps): JSX.Element => {
-  const { data: tournament } = useGetTournament(tournamentId ? { id: tournamentId } : 'skip');
+  const { data: tournament } = useGetTournament(tournamentId ? {
+    id: tournamentId,
+  } : 'skip');
+  const { data: tournamentCompetitors } = useGetTournamentCompetitorsByTournament(tournamentId ? {
+    tournamentId: tournamentId,
+  } : 'skip');
   const form = useForm<TournamentFormData>({
     defaultValues: {
       ...defaultValues,
@@ -57,7 +63,9 @@ export const TournamentForm = ({
     mode: 'onSubmit',
   });
   const onSubmit: SubmitHandler<TournamentFormData> = async (formData) => {
-    const data = validateForm(tournamentFormSchema, formData, form.setError as UseFormSetError<FieldValues>);
+    const data = validateForm(createSchema({
+      competitorCount: tournamentCompetitors?.length ?? 0,
+    }), formData, form.setError as UseFormSetError<FieldValues>);
     if (data) {
       handleSubmit({
         ...data,
diff --git a/src/components/TournamentForm/components/CompetitorFields.tsx b/src/components/TournamentForm/components/CompetitorFields.tsx
index 3bcd0529..b72f2551 100644
--- a/src/components/TournamentForm/components/CompetitorFields.tsx
+++ b/src/components/TournamentForm/components/CompetitorFields.tsx
@@ -89,7 +89,7 @@ export const CompetitorFields = ({
         <Switch checked={useTeams} onCheckedChange={handleToggleIsTeam} />
       </FormField>
       <div className={styles.Stackable}>
-        <FormField name="maxCompetitors" label={`Total ${getCompetitorLabel()}`} disabled={disableFields}>
+        <FormField name="maxCompetitors" label={`Total ${getCompetitorLabel()}`} disabled={!['draft', 'published'].includes(status)}>
           <InputText type="number" />
         </FormField>
         <Animate show={useTeams}>