diff --git a/core.js b/core.js
index 95a6467..c14bf4e 100644
--- a/core.js
+++ b/core.js
@@ -67,7 +67,8 @@ module.exports = function (xhr) {
 
       // Ensure that we have the appropriate request data.
       if (options.data == null && model && (method === 'create' || method === 'update' || method === 'patch')) {
-          params.json = options.attrs || model.toJSON(options);
+          params.body = options.attrs || model.toJSON(options);
+          params.json = true;
       }
 
       // If passed a data param, we add it to the URL or body depending on request type
@@ -82,7 +83,7 @@ module.exports = function (xhr) {
       // For older servers, emulate JSON by encoding the request into an HTML-form.
       if (options.emulateJSON) {
           params.headers['content-type'] = 'application/x-www-form-urlencoded';
-          params.body = params.json ? {model: params.json} : {};
+          params.body = params.json ? {model: params.body} : {};
           delete params.json;
       }
 
diff --git a/package.json b/package.json
index 0215d6c..57c9d89 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "media-type": "0.3.0",
     "qs": "^6.1.0",
     "request": "^2.55.0",
-    "xhr": "^2.0.5"
+    "xhr": "^2.3.1"
   },
   "devDependencies": {
     "ampersand-model": "^7.0.0",
diff --git a/test/unit.js b/test/unit.js
index f5bcb90..8d2d007 100644
--- a/test/unit.js
+++ b/test/unit.js
@@ -115,8 +115,8 @@ test('create', function (t) {
     }));
     t.equal(reqStub.recentOpts.url, '/library');
     t.equal(reqStub.recentOpts.method, 'POST');
-    t.ok(reqStub.recentOpts.json, 'body passed as json');
-    var data = reqStub.recentOpts.json;
+    t.equal(reqStub.recentOpts.json, true, 'json is set to true');
+    var data = reqStub.recentOpts.body;
     t.equal(data.title, 'The Tempest');
     t.equal(data.author, 'Bill Shakespeare');
     t.equal(data.length, 123);
@@ -130,8 +130,8 @@ test('update', function (t) {
     }));
     t.equal(reqStub.recentOpts.url, '/library');
     t.equal(reqStub.recentOpts.method, 'PUT');
-    t.ok(reqStub.recentOpts.json, 'body passed as json');
-    var data = reqStub.recentOpts.json;
+    t.equal(reqStub.recentOpts.json, true, 'json is set to true');
+    var data = reqStub.recentOpts.body;
     t.equal(data.id, '1-the-tempest');
     t.equal(data.author, 'William Shakespeare');
     t.end();
@@ -163,8 +163,8 @@ test('update with just emulateHTTP', function (t) {
     });
     t.equal(reqStub.recentOpts.url, '/library');
     t.equal(reqStub.recentOpts.method, 'POST');
-    t.ok(reqStub.recentOpts.json, 'body passed as json');
-    var data = reqStub.recentOpts.json;
+    t.equal(reqStub.recentOpts.json, true, 'json is set to true');
+    var data = reqStub.recentOpts.body;
     t.equal(data.id, '2-the-tempest');
     t.equal(data.author, 'Tim Shakespeare');
     t.equal(data.length, 123);
@@ -352,3 +352,21 @@ test('should parse json for different media types', function (t) {
     });
 });
 
+test('passing `body` in the opts should take precedence over the model\'s data', function (t) {
+	var model = modelStub({
+        title: 'The Tempest',
+        author: 'Bill Shakespeare',
+        length: 123
+    });
+
+    sync('create', model, {
+	    body: {
+		    rating: "5"
+	    }
+    });
+
+    t.equal(reqStub.recentOpts.json, true, 'json is set to true');
+    var data = reqStub.recentOpts.body;
+    t.equal(data.rating, '5');
+    t.end();
+});
\ No newline at end of file