Using ef core and trying to select parent items according to criteria in the child item.

If I was doing this in sql I would

 declare @UserName nvarchar(200) set @UserName = 'al65272' declare @ClientId int set @ClientId = 32 select u.* from AspNetUsers u inner join ClientUser cu on u.Id = cu.UserId where NormalizedUserName = upper(@UserName) and cu.ClientId=@ClientId 

I thought I could do something like this:

var userByUserName = _applicationDbContext.Users.FirstOrDefault(x => x.NormalizedUserName == userName.ToUpper() && x.ClientUsers.Contains(new ClientUser {ClientId = client.Id, User = x})); 

But obviously wrong as does not return anything.

Can anyone point me in the right direction?