diff --git a/addons/crm/crm_opportunity.py b/addons/crm/crm_opportunity.py
index 5869f94e72e..1b7658a1ff9 100644
--- a/addons/crm/crm_opportunity.py
+++ b/addons/crm/crm_opportunity.py
@@ -150,6 +150,19 @@ class crm_opportunity(osv.osv):
             return {'value':{}}
         return {'value':{'probability': stage.probability}}
 
+    def onchange_assign_id(self, cr, uid, ids, partner_assigned_id, context={}):
+        """This function updates the "assignation date" automatically, when manually assign a partner in the geo assign tab
+            @param self: The object pointer
+            @param cr: the current row, from the database cursor,
+            @param uid: the current user’s ID for security checks,
+            @param ids: List of stage’s IDs
+            @stage_id: change state id on run time """
+
+        if not partner_assigned_id:
+            return {'value':{'date_assign': False}}
+        else:
+            return {'value':{'date_assign': time.strftime('%Y-%m-%d')}}
+
     _defaults = {
         'company_id': lambda s,cr,uid,c: s.pool.get('res.company')._company_default_get(cr, uid, 'crm.lead', context=c),
         'priority': crm.AVAILABLE_PRIORITIES[2][0],
diff --git a/addons/crm/crm_opportunity_view.xml b/addons/crm/crm_opportunity_view.xml
index 406ec2eefd7..894a4e86ea3 100644
--- a/addons/crm/crm_opportunity_view.xml
+++ b/addons/crm/crm_opportunity_view.xml
@@ -182,7 +182,7 @@
                         <page string="Assignation" groups="base.group_extended">
                         <group name="partner_assign_group" col="5" colspan="4">
                             <separator string="Partner Assignation" colspan="5"/>
-                            <field name="partner_assigned_id"/>
+                            <field name="partner_assigned_id" on_change="onchange_assign_id(partner_assigned_id)"/>
                             <field name="date_assign"/>
                             <group colspan="1" col="1">
                                 <button string="Forward"