User blog comment:KevlarNinja/Spartan vs. Roman Centurion/@comment-3354681-20110205022340/@comment-2016768-20110205173508

The Centurions were dedicated fighters, supremely disciplined and loyal, with harsh punishments for even trifle crimes such as falling asleep on guard duty. They have more modern weaponry and tougher armor (lorica segmentate (or padded iron chainmail with leather above), scutums (shields), and iron breatplates) as well as the ability to adapt and crush armies in size many times larger than their own.

Besides (and I can't stress this enough) the Romans fought the Spartans at Pydna and who won? The Romans!