Regexp: extract first occurrence of date in string

I would like to extract first date from a string:

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

[1] "first date is 05.12.2009. Second date is 06.12.2009."

I tried:

sub("^.*?\\s(\\d{1,2}\\.\\d{1,2}\\.\\d{4})", "\\1", txt, extended=T, perl=T)

[1] "05.12.2009. Second date is 06.12.2009."

How to modify this?

-J