I see in forums, that lots of punters are using tennis favourites with 1.01-1.05 odds.
Personally i dont see fancy betting on favorites in such odds. There can be many thing that can happen-injuries, wind, rain or just bad day. Favorites can slip and competition is very high in tennis.
If uncertainty raises then it is good for weaker side.

Nadal 1.01 or Serena 1.01 odds are joke