diff --git a/addons/crm/wizard/crm_lead_to_opportunity_view.xml b/addons/crm/wizard/crm_lead_to_opportunity_view.xml
index d41030789b6..5f0e26a7dc5 100644
--- a/addons/crm/wizard/crm_lead_to_opportunity_view.xml
+++ b/addons/crm/wizard/crm_lead_to_opportunity_view.xml
@@ -46,6 +46,9 @@
                <form string="Create a Partner">
                 <label string="Are you sure you want to create a partner based on this lead ?" colspan="4"/>
                 <label string="You may have to verify that this partner does not exist already." colspan="4"/>
+                <group colspan="4" col="1" attrs="{'invisible':[('msg','=',False)]}">
+                    <field name="msg" colspan="4" nolabel="1"  height="50"/>
+                </group>
                 <newline />
                 <field name="action"/>
                 <group attrs="{'invisible':[('action','!=','exist')]}">
diff --git a/addons/crm/wizard/crm_lead_to_partner.py b/addons/crm/wizard/crm_lead_to_partner.py
index ea70248aed4..21c95442371 100644
--- a/addons/crm/wizard/crm_lead_to_partner.py
+++ b/addons/crm/wizard/crm_lead_to_partner.py
@@ -33,7 +33,8 @@ class crm_lead2partner(osv.osv_memory):
         'action': fields.selection([('exist', 'Link to an existing partner'), \
                                     ('create', 'Create a new partner')], \
                                     'Action', required=True),
-        'partner_id': fields.many2one('res.partner', 'Partner')
+        'partner_id': fields.many2one('res.partner', 'Partner'),
+        'msg': fields.text('Message', readonly=True)
         }
 
     def view_init(self, cr, uid, fields, context=None):
@@ -76,12 +77,19 @@ class crm_lead2partner(osv.osv_memory):
 
         for lead in lead_obj.browse(cr, uid, data, context=context):
             partner_ids = []
-            if lead.email_from:
-                email = re.findall(r'([^ ,<@]+@[^> ,]+)', lead.email_from)
-                address_ids = contact_obj.search(cr, uid, [('email', 'in', email)])
+            # Find partner address matches the email_from of the lead
+            email = re.findall(r'([^ ,<@]+@[^> ,]+)', lead.email_from or '')
+            email = map(lambda x: "'" + x + "'", email)
+            if email:
+                cr.execute("""select id from res_partner_address 
+                                where 
+                                substring(email from '([^ ,<@]+@[^> ,]+)') in (%s)""" % (','.join(email)))
+                address_ids = map(lambda x: x[0], cr.fetchall())
                 if address_ids:
                     addresses = contact_obj.browse(cr, uid, address_ids)
                     partner_ids = addresses and [addresses[0].partner_id.id] or False
+
+            # Find partner name that matches the name of the lead
             if not partner_ids and lead.partner_name:
                 partner_ids = partner_obj.search(cr, uid, [('name', '=', lead.partner_name)], context=context)
             if not partner_ids:
@@ -90,6 +98,26 @@ class crm_lead2partner(osv.osv_memory):
                 partner_ids = map(lambda x: x[0], cr.fetchall())
             partner_id = partner_ids and partner_ids[0] or False
 
+            if not partner_id:
+                label = False
+                opp_ids = []
+                if email:
+                    # Find email of existing opportunity matches the email_from of the lead
+                    cr.execute("""select id from crm_lead 
+                                where type='opportunity' and
+                                substring(email_from from '([^ ,<@]+@[^> ,]+)') in (%s)""" % (','.join(email)))
+                    opp_ids = map(lambda x:x[0], cr.fetchall())
+                    label = opp_ids and 'email' or False
+                if not opp_ids:
+                    # Find name of existing opportunity matches the name of the lead
+                    cr.execute("""SELECT l.id from crm_lead l
+                                    where type = 'opportunity' and
+                                    regexp_replace(lower(l.name), '[^a-z]*', '', 'g') = regexp_replace(%s, '[^a-z]*', '', 'g')""", (lead.name.lower(), ))
+                    opp_ids = map(lambda x: x[0], cr.fetchall())
+                    label = opp_ids and 'name' or False
+                if label:
+                    res.update({'msg': "An existing opportunity seems to match the %s of this lead, you should double-check before converting it." % (label)})
+
             if 'partner_id' in fields:
                 res.update({'partner_id': partner_id})
             if 'action' in fields: