Querying elements that match the query from an array within a document Mongodb

Question

There have been questions with similar titles, but none of them seem to suit my needs.

{
   '_id': '4e51b88f-b62f-4b62-81208e6011c9a388', 
   'name': 'dinky', 'phone': '91216098', 
   'blacklist': False, 
   'events': [
        {
          'startsAt': '2018-07-16T18:00:53.397', 
          'endsAt': '2018-07-16T18:10:53.397', 
          'title': 'dinky Appointment', 
          'note': ''
        }, 
        {
           'startsAt': '2018-07-30T18:00:00.000', 
           'endsAt': '2018-07-30T18:10:00.000', 
           'title': 'dinky', 
           'note': ''
        }, 
        {
           'startsAt': '2018-08-02T18:08:54.247', 
           'endsAt': '2018-08-02T18:18:54.247', 
           'title': 'dinky', 
           'note': ''
        }, 
        {
           'startsAt': '2018-08-09T18:45:09.146', 
           'endsAt': '2018-08-09T18:55:09.146', 
           'title': 'dinky', 
           'note': ''
         }
    ], 
  'additionalPhones': []
}

The above is a sample document. I want to query base on event.startsAt date. The result I want are events that match that date.

This is what I have tried.

todaysEvent = db.find({"events": { "$elemMatch": {"startsAt": { "$regex": "2018-08-09" }}}} )

However, when I used this, I end up getting documents that have events from this day, but it shows all other events that are not part of that date. I only want to show events that match that date.

FYI, I am using pymongo.

Thank you!