# In tennis how to call a service ball close to the intersection of the service lines

What happens in tennis when a ball hits the 'service line' but you are unsure if it also touched the 'central service line' to call it in?

For example in the drawing the player serving must throw the ball to the left service box, it is clear that the ball is not long because it touched the service line but how to tell if it is left enough?

It might be touching the center line but you don't know for sure because those two lines merge. Even with hawk eye you won't see the limit of the center line because it merges with the service line and both are white.

Any example of a hawk eye challenge like that?

• What level of play are you interested in, and what role do you have in this scenario? Obviously at high level tournaments, there are separate line judges for each line so this problem becomes trivial. Sep 6, 2022 at 7:28
• Further, HawkEye knows exactly where the separate lines are, even if a human can't see the difference.
– Nij
Sep 6, 2022 at 7:49
• How is it trivial?. When they challenge it all depends on differentiating the green from the white but in this case it's the white from the white. Sep 6, 2022 at 14:14
• When they challenge, there is no colour at all involved, just mathematical expressions and numerical results, either the number is small enough or it is not.
– Nij
Sep 6, 2022 at 23:34