Interesting discussion about Estonian names on last page !
I remember Estonian Fed Cup captain Rene Busch. That`s a German surname.
Also Jürgen Zopp has a German surname. Erika Hendsel, Anett Schutting too.
I also found many Estonian former WTA players on ITF site with German surname: Birgit Burk, Kristina Grünberg, Helene Holter, Barbara Kvelstein, Sandra Kvelstein, Helina Lill, Katri Miller, Monica Peets, Heike-Brit Ross, Merike Stamberg. BTW "Berg" = "mountain".
Estonian former ATP players with German surname I found on ITF site are: Rauno Gull, Allar Hint, Alexsander Jürgens, Sven Kasper, Markus Kerner, Mikhel Koppel, Peeter Lamp, Hendrik Lutter, Heggert Meier, Redt Reimal, Simmo Sommer, Sten Sumberg, Kaarel Tramm, Gert Vilms, Fredi Voormann, Viljar Zilmer.
Kontaveit could be an Estonian surname
As far as I know Kontaveit is not a German surname. At least I have never heard this surname here. I also have not heard anything similar.
Definitely an interesting topic