diff --git a/docs/topics/api.rst b/docs/topics/api.rst
index 57b8ee0cf..2055682dc 100644
--- a/docs/topics/api.rst
+++ b/docs/topics/api.rst
@@ -101,7 +101,7 @@ how you :ref:`configure the downloader middlewares
 
 .. class:: CrawlerRunner(settings)
 
-    This is a convenient helper class that creates, configures and runs
+    This is a convenient helper class that keeps track of, manages and runs
     crawlers inside an already setup Twisted `reactor`_.
 
     The CrawlerRunner object must be instantiated with a
@@ -116,23 +116,23 @@ how you :ref:`configure the downloader middlewares
        Set of :class:`crawlers <scrapy.crawler.Crawler>` created by the
        :meth:`crawl` method.
 
-    .. attribute:: crawl_deferreds
+    .. method:: crawl(crawler_or_spidercls, \*args, \**kwargs)
 
-       Set of the `deferreds`_ return by the :meth:`crawl` method. This
-       collection it's useful for keeping track of current crawling state.
+       This method runs a crawler with the provided arguments.
 
-    .. method:: crawl(spidercls, \*args, \**kwargs)
+       It will keep track of the given crawler so it can be stopped later,
+       while calling its :meth:`Crawler.crawl` method.
 
-       This method sets up the crawling of the given `spidercls` with the
-       provided arguments.
-
-       It takes care of loading the spider class while configuring and starting
-       a crawler for it.
+       If `crawler_or_spidercls` isn't a :class:`~scrapy.crawler.Crawler`
+       instance, it will try to create one using this parameter as the spider
+       class given to it.
 
        Returns a deferred that is fired when the crawl is finished.
 
-       :param spidercls: spider class or spider's name inside the project
-       :type spidercls: :class:`~scrapy.spider.Spider` subclass or str
+       :param crawler_or_spidercls: already created crawler, or a spider class
+       or spider's name inside the project to create it
+       :type crawler_or_spidercls: :class:`~scrapy.crawler.Crawler` instance,
+        :class:`~scrapy.spider.Spider` subclass or string
 
        :param args: arguments to initializate the spider
        :type args: list
diff --git a/scrapy/crawler.py b/scrapy/crawler.py
index 692a896be..615303528 100644
--- a/scrapy/crawler.py
+++ b/scrapy/crawler.py
@@ -82,9 +82,12 @@ class CrawlerRunner(object):
         self.crawlers = set()
         self._active = set()
 
-    def crawl(self, spidercls, *args, **kwargs):
-        crawler = self._create_crawler(spidercls)
-        self._setup_crawler_logging(crawler)
+    def crawl(self, crawler_or_spidercls, *args, **kwargs):
+        crawler = crawler_or_spidercls
+        if not isinstance(crawler_or_spidercls, Crawler):
+            crawler = self._create_crawler(crawler_or_spidercls)
+            self._setup_crawler_logging(crawler)
+
         self.crawlers.add(crawler)
         d = crawler.crawl(*args, **kwargs)
         self._active.add(d)