while ( <DATA> ) {
  if ( /^(\d+\/123 11.*?) a / ) { #first matched
    my $first = $1;
    my $second = $1 if /\G.*?zyx(.*)/; #check for next match
    print "First = $first\n";
    #print $second only if it is defined;
    print "Second = $second\n" if defined $second; 
  }

}