c:\@Work\Perl\monks>perl -wMstrict -le
"for my $d ('aaaa 987', 'no joy',) {
   printf qq{'$d': };
   if (my ($x, $y) = $d =~ m{ \A (a+) \s+ (\d+) \z }xms) {
     print qq{match: x is '$x'; y is '$y'};
     }
   else {
     print 'no match';
     }
   }
"
'aaaa 987': match: x is 'aaaa'; y is '987'
'no joy': no match