Juan Pablo Angel belatedly produced his best goalscoring performance in Aston Villa's runaway win.
Villa though coasted to their first win of the season under the control of new manager, David O'Leary.
It was also only Villa's second win in 18 games against Leicester over the last 15 years.
O'Leary said: "I was very pleased with our start but disappointed with our second-half performance against ten players.
"I'm hoping that Angel's two goals will be a big boost to him although he will now be absent for the next fortnight because of international duty."
Micky Adams, Leicester's boss, was far from pleased. He said: "Our defensive failings were exposed and the game was over for us after the first 15 minutes.
"I didn't take anything positive from the game and we are now back to square one."
Villa were flying from the start, while Leicester were always struggling after losing John Curtis in only the second minute.
Leicester's problems were compounded in the eighth minute when a corner from the left by Lee Hendrie was headed goalwards by Darius Vassell only for Ben Thatcher to turn the ball into his own net.
Angel struck in the next minute with his first league goal since scoring against Fulham last November at Villa Park.
The Leicester defence was at fault as Peter Whittingham crossed the ball in from the left to give the Colombian international a free header.
Leicester were completely bemused by Villa's attack and Angel responded with his second goal in the 15th minute when he turned a low left-wing cross from Whittingham past Walker at the near post.
Only a desperate clearance by Andy Impey prevented Mark Delaney scoring a fourth goal in the 33rd minute following a five-man close passing movement.
Ferdinand's dismissal occurred after he had words with both the linesman and referee which produced two yellow cards as the aggrieved former England striker continued to argue.
Muzzy Izzet pulled back a goal in the 54th minute direct from a free kick which had been moved forward several yards by the referee as a punishment imposed on Ronny Johnsen who was booked in the incident.