There's nothing stopping you from using a regular expression. As long as you escape the meta characters, $variables will work just in a regex.

my $count = 0;
while (<FILE>){ 
    $count++ if /\Q$src/ && /\Q$sport/;
}
print "Both found a total of $count times\n";
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- Miller

Update: (03:58 UTC) Ahh, misunderstand "beforehand". I second that kyle's reply is the way to go.