diff --git a/src/create.ts b/src/create.ts
index a6628d0..ab7fd2d 100644
--- a/src/create.ts
+++ b/src/create.ts
@@ -351,9 +351,8 @@ export class Create {
         if (this.stage.type === 'round_robin' && opponent1 === null && opponent2 === null)
             return;
 
-        const status = helpers.getMatchByeStatus(opponents);
-
         let existing: Match | null = null;
+        let status = helpers.getMatchStatus(opponents);
 
         if (this.updateMode) {
             existing = await this.storage.selectFirst('match', {
@@ -363,6 +362,13 @@ export class Create {
 
             const currentChildCount = existing?.child_count;
             childCount = currentChildCount === undefined ? childCount : currentChildCount;
+
+            if (existing) {
+                // Keep the most advanced status when updating a match.
+                const existingStatus = helpers.getMatchStatus(existing);
+                if (existingStatus > status)
+                    status = existingStatus;
+            }
         }
 
         const parentId = await this.insertMatch({
@@ -706,7 +712,8 @@ export class Create {
         if (!existing)
             return this.storage.insert('match', match);
 
-        if (!await this.storage.update('match', existing.id, { ...existing, ...helpers.getUpdatedMatchResults(match) }))
+        const updated = helpers.getUpdatedMatchResults(match, existing) as Match;
+        if (!await this.storage.update('match', existing.id, updated))
             throw Error('Could not update the match.');
 
         return existing.id;
@@ -730,7 +737,8 @@ export class Create {
         if (!existing)
             return this.storage.insert('match_game', matchGame);
 
-        if (!await this.storage.update('match_game', existing.id, { ...existing, ...helpers.getUpdatedMatchResults(matchGame) }))
+        const updated = helpers.getUpdatedMatchResults(matchGame, existing) as MatchGame;
+        if (!await this.storage.update('match_game', existing.id, updated))
             throw Error('Could not update the match game.');
 
         return existing.id;
diff --git a/src/helpers.ts b/src/helpers.ts
index 04dadf7..a859c4d 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -591,18 +591,6 @@ export function isMatchParticipantLocked(match: MatchResults): boolean {
     return match.status >= Status.Running;
 }
 
-/**
- * Returns the status of a match based on the presence of the opponents.
- *
- * @param opponents The opponents of a match.
- */
-export function getMatchByeStatus(opponents: Duel): Status {
-    return getMatchStatus({
-        opponent1: opponents[0],
-        opponent2: opponents[1],
-    });
-}
-
 /**
  * Indicates whether a match has at least one BYE or not.
  * 
@@ -612,12 +600,31 @@ export function hasBye(match: Partial<MatchResults>): boolean {
     return match.opponent1 === null || match.opponent2 === null;
 }
 
+/**
+ * Returns the status of a match based on the opponents of a match.
+ * 
+ * @param opponents The opponents of a match.
+ */
+export function getMatchStatus(opponents: Duel): Status;
+
 /**
  * Returns the status of a match based on the results of a match.
  *
  * @param match Partial match results.
  */
-export function getMatchStatus(match: Partial<MatchResults>): Status {
+export function getMatchStatus(match: Partial<MatchResults>): Status;
+
+/**
+ * Returns the status of a match based on information about it.
+ * 
+ * @param arg The opponents or partial results of the match.
+ */
+export function getMatchStatus(arg: Duel | Partial<MatchResults>): Status {
+    const match = Array.isArray(arg) ? {
+        opponent1: arg[0],
+        opponent2: arg[1],
+    } : arg;
+
     if (hasBye(match)) // At least one BYE.
         return Status.Locked;
 
@@ -1250,12 +1257,14 @@ export function getParentMatchResults(storedParent: Match, scores: Scores): Part
  * Gets the values which need to be updated in a match when it's updated on insertion.
  *
  * @param match The up to date match.
+ * @param existing The base match.
  */
-export function getUpdatedMatchResults(match: MatchResults): MatchResults {
+export function getUpdatedMatchResults<T extends MatchResults>(match: T, existing: T): T {
     return {
-        status: match.status,
-        opponent1: match.opponent1,
-        opponent2: match.opponent2,
+        ...existing,
+        ...match,
+        opponent1: { ...existing.opponent1, ...match.opponent1 },
+        opponent2: { ...existing.opponent2, ...match.opponent2 },
     };
 }
 
diff --git a/test/update.spec.js b/test/update.spec.js
index 4953c7e..bb1b650 100644
--- a/test/update.spec.js
+++ b/test/update.spec.js
@@ -665,6 +665,54 @@ describe('Seeding', () => {
         assert.strictEqual((await storage.select('participant')).length, 8 + 6);
     });
 
+    it('should update the seeding and keep completed matches completed', async () => {
+        await manager.update.seeding(0, [
+            'Team 1', 'Team 2',
+            'Team 3', 'Team 4',
+            'Team 5', 'Team 6',
+            'Team 7', 'Team 8',
+        ]);
+
+        await manager.update.match({
+            id: 0,
+            opponent1: { score: 1, result: 'win' },
+            opponent2: { score: 0 },
+        });
+
+        await manager.update.seeding(0, [
+            'Team 1', 'Team 2', // Keep this pair.
+            'Team 4', 'Team 3',
+            'Team 6', 'Team 5',
+            'Team 8', 'Team 7',
+        ]);
+
+        const match = await storage.select('match', 0);
+        assert.strictEqual(match.opponent1.result, 'win');
+        assert.strictEqual(match.status, Status.Completed);
+    });
+
+    it('should throw if a match is completed and would have to be changed', async () => {
+        await manager.update.seeding(0, [
+            'Team 1', 'Team 2',
+            'Team 3', 'Team 4',
+            'Team 5', 'Team 6',
+            'Team 7', 'Team 8',
+        ]);
+
+        await manager.update.match({
+            id: 0,
+            opponent1: { score: 1, result: 'win' },
+            opponent2: { score: 0 },
+        });
+
+        await assert.isRejected(manager.update.seeding(0, [
+            'Team 2', 'Team 1', // Change this pair.
+            'Team 3', 'Team 4',
+            'Team 5', 'Team 6',
+            'Team 7', 'Team 8',
+        ]), 'A match is locked.');
+    });
+
     it('should throw if a match is locked and would have to be changed', async () => {
         await manager.update.seeding(0, [
             'Team 1', 'Team 2',