There are a number of ways to do what you want.
- anchor to the end to get the last word match
- use list slice to get last or even second to last word

my ($last) = $in =~ m/(\w+)$/i;
print "last=$last\n";   

my ($second_to_last) = ($in =~ m/(\w+)/gi)[-2]; #[-1] would have been 
+last
print "second to last=$second_to_last\n";

__END__
Prints:
last=senthil
second to last=foo
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Note that Perl shortcut of \w also includes _0-9 Often this doesn't matter and I just use the \w instead of making a special set.