The Blades lost 3-0 at Portman Road but were fuming after three penalty appeals were turned down by the official.
Lester has vented his fury with an amazing outburst at Fletcher and his linesmen, saying that they were doing their best to hand the Suffolk side the win.
"The ref's a spastic," fumed Lester.
"He was very weak and very poor and he and his linesmen were determined to make Ipswich win.
"But we couldn't do anything about it because the ref refused to talk to us during or after the game. He's just a weak individual."
Lester was involved in two penalty shouts for the visitors, the second of which resulted in his shirt being ripped and his back cut after a mauling from Georges Santos, but no spot kick was awarded.
"All three were definite penalties but I can't believe he didn't give the last one. My shirt was ripped and my back was cut, yet he gave them the free kick."
Lester's comments are sure to cause a storm and may land him in heavy bother with The Football Association.
