diff --git a/src/EFCore.PG/Storage/Internal/NpgsqlRelationalConnection.cs b/src/EFCore.PG/Storage/Internal/NpgsqlRelationalConnection.cs
index 3788670e0..87bce1171 100644
--- a/src/EFCore.PG/Storage/Internal/NpgsqlRelationalConnection.cs
+++ b/src/EFCore.PG/Storage/Internal/NpgsqlRelationalConnection.cs
@@ -17,6 +17,9 @@ public class NpgsqlRelationalConnection : RelationalConnection, INpgsqlRelationa
     private readonly ProvideClientCertificatesCallback? _provideClientCertificatesCallback;
     private readonly RemoteCertificateValidationCallback? _remoteCertificateValidationCallback;
 
+    // True when a connection was supplied after construction, e.g. via Database.SetDbConnection(). It isn't reflected in the options.
+    private bool _isDbConnectionSet;
+
 #pragma warning disable CS0618 // ProvidePasswordCallback is obsolete
     private readonly ProvidePasswordCallback? _providePasswordCallback;
 #pragma warning restore CS0618
@@ -147,6 +150,19 @@ public override string? ConnectionString
         }
     }
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public override void SetDbConnection(DbConnection? value, bool contextOwnsConnection)
+    {
+        base.SetDbConnection(value, contextOwnsConnection);
+
+        _isDbConnectionSet = value is not null;
+    }
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -205,7 +221,7 @@ public virtual INpgsqlRelationalConnection CreateAdminConnection()
         // Cloned connections must be owned so disposing the wrapper also closes and disposes them.
         var adminNpgsqlOptions = DataSource is not null
             ? npgsqlOptions.WithConnection(((NpgsqlConnection)CreateDbConnection()).CloneWith(adminConnectionString), owned: true)
-            : npgsqlOptions.Connection is not null
+            : npgsqlOptions.Connection is not null || _isDbConnectionSet
                 ? npgsqlOptions.WithConnection(DbConnection.CloneWith(adminConnectionString), owned: true)
                 : npgsqlOptions.WithConnectionString(adminConnectionString);
 
diff --git a/test/EFCore.PG.FunctionalTests/ConnectionSpecificationTest.cs b/test/EFCore.PG.FunctionalTests/ConnectionSpecificationTest.cs
index c16a173f0..6a96209e7 100644
--- a/test/EFCore.PG.FunctionalTests/ConnectionSpecificationTest.cs
+++ b/test/EFCore.PG.FunctionalTests/ConnectionSpecificationTest.cs
@@ -278,6 +278,33 @@ public async Task Can_create_admin_connection_with_connection()
         adminConnection.Open();
     }
 
+    [Fact]
+    public async Task Can_create_admin_connection_with_connection_set_via_SetDbConnection()
+    {
+        await using var _ = await NpgsqlTestStore.GetNorthwindStoreAsync();
+
+        // Once opened, Npgsql removes the password from the connection's ConnectionString (Persist Security Info=false), so the admin
+        // connection must be cloned from the connection rather than rebuilt from its connection string.
+        await using var connection = new NpgsqlConnection(NpgsqlTestStore.NorthwindConnectionString);
+        await connection.OpenAsync();
+
+        var optionsBuilder = new DbContextOptionsBuilder<GeneralOptionsContext>();
+        optionsBuilder.UseNpgsql(b => b.ApplyConfiguration());
+        await using var context = new GeneralOptionsContext(optionsBuilder.Options);
+        context.Database.SetDbConnection(connection);
+
+        var relationalConnection = context.GetService<INpgsqlRelationalConnection>();
+        await using (var adminConnection = relationalConnection.CreateAdminConnection())
+        {
+            Assert.Equal("postgres", new NpgsqlConnectionStringBuilder(adminConnection.ConnectionString).Database);
+
+            await adminConnection.OpenAsync(CancellationToken.None);
+        }
+
+        // Disposing the admin connection must not dispose the connection supplied by the user
+        Assert.Equal(System.Data.ConnectionState.Open, connection.State);
+    }
+
     private class GeneralOptionsContext(DbContextOptions<GeneralOptionsContext> options) : NorthwindContextBase(options);
 
     #endregion