Filter list of embedded documents with reference f

Question

I'm pretty new to MongoDB and I'm experiencing it with mongoengine. Given this 'User' model where 'bets' is an embedded document list which each element contains a reference to a 'match' document,

{ 
  "_id" : ObjectId("53df77cef4c9610f28cbff14"), 
  "name" : "Test", 
  "admin" : false, 
  "bets" : [ 
             { "match" : ObjectId("53e1511df4c9610bf52f5b7a"), "expectedResult" : "1" } 
           ] 
 }

how can I get 'bets' elements, passed to query the matchId?

I tried to do

User.objects.filter(bets__match={'match._id':match.id})

where 'match' is the object I need to filter by but I get an empty array.