manuel pellegrini has the most difficult job in football , according to west ham boss sam allardyce .
city entertain the hammers at the etihad stadium on sunday with speculation over pellegrini 's future mounting after a difficult season and a run of six defeats in their last eight games .
but allardyce believes the pressure of going for back-to-back league titles , plus the introduction of financial fair play -lrb- ffp -rrb- rules .