bash - How to use grep to match two strings in the same line

How can I use grep to find two terms / strings in one line?
The output, or an entry in the log file, should only be made if the two terms / strings have been found.
I have made the following attempts:

egrep -n --color '(string1.*string2)' debuglog.log

In this example, everything between the two strings is marked.
But I would like to see only the two found strings marked.
Is that possible?
Maybe you could do this with another tool, I am open for suggestions.