This afternoon's running of the Melbourne Cup has been reduced to a field of 22 after Godolphin horse Cavalryman pulling out of the race this morning.

The nine-year-old has a swollen fetlock and was examined by vets before the big race and wasn't passed fit.

The solid English stayer finished 12th in the Melbourne Cup in 2012 and was priced at $26 by the New Zealand TAB to win this year.