[{"_id":ObjectId("5fbf3afe1ecd92296c746db6"),"name":"1st Testing Tournament","player":[{"paid":false,"_id":ObjectId("5fbf3cfe6347784028da8181"),"user":ObjectId("5fbf3b4c1ecd92296c746dcd")}]}]

db.collection.update({_id:ObjectId("5fbf3afe1ecd92296c746db6"),"player.user":ObjectId("5fbf3b4c1ecd92296c746dcd")},{$set:{"player.$.paid":true}})