split's default behavior will split on multiple whitespace, much like /\s+/, with the bonus of ignoring leading and trailing whitespace:

use strict;
use warnings;

while (<DATA>) {
    print "The fourth element is ", (split)[3], "\n";
}

__DATA__
one two three      four five           six seven
   A B             C D E F G H  I
spam              eggs spam spam and spam
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