diff --git a/src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonInputFormatter.cs b/src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonInputFormatter.cs
index bb21bc64df..d93260032f 100644
--- a/src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonInputFormatter.cs
+++ b/src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonInputFormatter.cs
@@ -118,6 +118,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             }
             else
             {
+                Log.JsonInputSuccess(_logger, context.ModelType);
                 return InputFormatterResult.Success(model);
             }
         }
@@ -134,18 +135,26 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
         private static class Log
         {
-            private static readonly Action<ILogger, Exception> _jsonInputFormatterException;
+            private static readonly Action<ILogger, string, Exception> _jsonInputFormatterException;
+            private static readonly Action<ILogger, string, Exception> _jsonInputSuccess;
 
             static Log()
             {
-                _jsonInputFormatterException = LoggerMessage.Define(
-                   LogLevel.Debug,
-                   new EventId(1, "SystemTextJsonInputException"),
-                   "JSON input formatter threw an exception.");
+                _jsonInputFormatterException = LoggerMessage.Define<string>(
+                    LogLevel.Debug,
+                    new EventId(1, "SystemTextJsonInputException"),
+                    "JSON input formatter threw an exception: {Message}");
+                _jsonInputSuccess = LoggerMessage.Define<string>(
+                    LogLevel.Debug,
+                    new EventId(2, "SystemTextJsonInputSuccess"),
+                    "JSON input formatter succeeded, deserializing to type '{TypeName}'");
             }
 
             public static void JsonInputException(ILogger logger, Exception exception) 
-                => _jsonInputFormatterException(logger, exception);
+                => _jsonInputFormatterException(logger, exception.Message, exception);
+
+            public static void JsonInputSuccess(ILogger logger, Type modelType)
+                => _jsonInputSuccess(logger, modelType.FullName, null);
         }
     }
 }
diff --git a/src/Mvc/Mvc.Core/test/Formatters/JsonInputFormatterTestBase.cs b/src/Mvc/Mvc.Core/test/Formatters/JsonInputFormatterTestBase.cs
index fe94632904..af680361ea 100644
--- a/src/Mvc/Mvc.Core/test/Formatters/JsonInputFormatterTestBase.cs
+++ b/src/Mvc/Mvc.Core/test/Formatters/JsonInputFormatterTestBase.cs
@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.IO;
+using System.Linq;
 using System.Text;
 using System.Text.Json;
 using System.Threading.Tasks;
@@ -18,6 +19,14 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 {
     public abstract class JsonInputFormatterTestBase : LoggedTest
     {
+        internal enum Formatter
+        {
+            Newtonsoft,
+            SystemText
+        }
+
+        internal abstract Formatter CurrentFormatter { get; }
+
         [Theory]
         [InlineData("application/json", true)]
         [InlineData("application/*", false)]
@@ -106,6 +115,67 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             Assert.Equal("abcd", stringValue);
         }
 
+        [Fact]
+        public async Task JsonFormatter_EscapedKeys_Bracket()
+        {
+            // Arrange
+            var content = "[{\"It[s a key\":1234556}]";
+            var formatter = GetInputFormatter();
+
+            var contentBytes = Encoding.UTF8.GetBytes(content);
+            var httpContext = GetHttpContext(contentBytes);
+
+            var formatterContext = CreateInputFormatterContext(typeof(IEnumerable<IDictionary<string, short>>), httpContext);
+
+            // Act
+            var result = await formatter.ReadAsync(formatterContext);
+
+            // Assert
+            Assert.True(result.HasError);
+            Assert.Collection(
+                formatterContext.ModelState.OrderBy(k => k.Key),
+                kvp =>
+                {
+                    Assert.Equal("[0][\'It[s a key\']", kvp.Key);
+                });
+        }
+
+        [Fact]
+        public async Task JsonFormatter_EscapedKeys()
+        {
+            // Arrange
+            var content = "[{\"It\\\"s a key\": 1234556}]";
+            var formatter = GetInputFormatter();
+
+            var contentBytes = Encoding.UTF8.GetBytes(content);
+            var httpContext = GetHttpContext(contentBytes);
+
+            var formatterContext = CreateInputFormatterContext(
+                typeof(IEnumerable<IDictionary<string, short>>), httpContext);
+
+            // Act
+            var result = await formatter.ReadAsync(formatterContext);
+
+            // Assert
+            Assert.True(result.HasError);
+            Assert.Collection(
+                formatterContext.ModelState.OrderBy(k => k.Key),
+                kvp =>
+                {
+                    switch(CurrentFormatter)
+                    {
+                        case Formatter.Newtonsoft:
+                            Assert.Equal("[0]['It\"s a key']", kvp.Key);
+                            break;
+                        case Formatter.SystemText:
+                            Assert.Equal("[0][\'It\\u0022s a key\']", kvp.Key);
+                            break;
+                        default:
+                            throw new NotImplementedException();
+                    }
+                });
+        }
+
         [Fact]
         public virtual async Task JsonFormatterReadsDateTimeValue()
         {
@@ -280,7 +350,12 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
             // Assert
             Assert.True(result.HasError);
-            Assert.Single(formatterContext.ModelState["names[1].Small"].Errors);
+            Assert.Collection(
+                formatterContext.ModelState.OrderBy(k => k.Key),
+                kvp => {
+                    Assert.Equal("names[1].Small", kvp.Key);
+                    Assert.Single(kvp.Value.Errors);
+                });
         }
 
         [Fact]
diff --git a/src/Mvc/Mvc.Core/test/Formatters/SystemTextJsonInputFormatterTest.cs b/src/Mvc/Mvc.Core/test/Formatters/SystemTextJsonInputFormatterTest.cs
index aa43db0221..9ef9630a45 100644
--- a/src/Mvc/Mvc.Core/test/Formatters/SystemTextJsonInputFormatterTest.cs
+++ b/src/Mvc/Mvc.Core/test/Formatters/SystemTextJsonInputFormatterTest.cs
@@ -13,6 +13,8 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 {
     public class SystemTextJsonInputFormatterTest : JsonInputFormatterTestBase
     {
+        internal override Formatter CurrentFormatter => Formatter.SystemText;
+
         [Fact]
         public override Task ReadAsync_AddsModelValidationErrorsToModelState()
         {
diff --git a/src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonInputFormatter.cs b/src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonInputFormatter.cs
index 438f996032..49a5581b87 100644
--- a/src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonInputFormatter.cs
+++ b/src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonInputFormatter.cs
@@ -227,6 +227,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
                         else
                         {
                             addMember = !path.EndsWith("." + member, StringComparison.Ordinal)
+                                && !path.EndsWith("['" + member + "']", StringComparison.Ordinal)
                                 && !path.EndsWith("[" + member + "]", StringComparison.Ordinal);
                         }
                     }
diff --git a/src/Mvc/Mvc.NewtonsoftJson/test/NewtonsoftJsonInputFormatterTest.cs b/src/Mvc/Mvc.NewtonsoftJson/test/NewtonsoftJsonInputFormatterTest.cs
index b1a2234a5d..fa29d0289f 100644
--- a/src/Mvc/Mvc.NewtonsoftJson/test/NewtonsoftJsonInputFormatterTest.cs
+++ b/src/Mvc/Mvc.NewtonsoftJson/test/NewtonsoftJsonInputFormatterTest.cs
@@ -24,6 +24,8 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         private static readonly ObjectPoolProvider _objectPoolProvider = new DefaultObjectPoolProvider();
         private static readonly JsonSerializerSettings _serializerSettings = new JsonSerializerSettings();
 
+        internal override Formatter CurrentFormatter => Formatter.Newtonsoft;
+
         [Fact]
         public async Task Constructor_BuffersRequestBody_UsingDefaultOptions()
         {
@@ -253,7 +255,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
             // Assert
             Assert.Collection(
-                formatterContext.ModelState.OrderBy(k => k),
+                formatterContext.ModelState.OrderBy(k => k.Key),
                 kvp =>
                 {
                     Assert.Equal("[1]", kvp.Key);