Originally Posted by 5555
Tennis expert is a person who is very knowledgeable about tennis.
Knowledge about a subject enables you to establish what is likely to happen in future.
The best evidence of expertise is proof that a person is widely recognized as a expert.
Yes, but how do you determine who is very knowledgeable??
And not, "widely regonized" is not a proof. Millions of people may believe/think something and still be wrong.