How to unit-test this method?

I have a method and it is also the method that I am trying to write a test for:

public IPlayerResponse GetPlayerStats(IPlayerRequest playerRequest)
{
    string playerId = playerRequest.PlayerId;

    string requestUri = playerId + "/evaluate";

     var request = new HttpRequestMessage(HttpMethod.Post, requestUri)
                                {
                                    Content = new StringContent
            (JsonConvert.SerializeObject(playerRequest),
             System.Text.Encoding.UTF8,
            "application/json")
          };

      var response = _client
    .SendAsync(request, CancellationToken.None)
    .Result;
     var responseContent = response.
    Content
    .ReadAsStringAsync()
    .Result;



    var playerResponseModel =    
    JsonConvert.DeserializeObject<PlayerResponseModel>(responseContent);
    var playerResponse = _mapper
.Map<IPlayerResponse>(playerResponseModel);

return playerResponse;
 }

The request interface:

public interface IPlayerRequest
    {
        IEnumerable<IPlayerStatsItem> Items { get; set; }
        string PlayerId { get; set; }
    }

I plan to write a test for this method and send the sample data for IPlayerRequest to get the response against a deployed end point. I have the TestSetup ready for hitting the endpoint.

What is the ideal way to mock the IPlayerRequest and populate it with some data to get a response?