"To win at Anfield is fantastic," said Friedel. "With the result last year, it does leave a bad taste in the mouth. It's not revenge, but it's pleasing to put in a performance because last year we just didn't turn up."
The 38-year-old Friedel was outstanding the second half when Liverpool piled on the pressure after falling, 2-0, behind.
He stopped Steven Gerrard with a diving stop and later made saves on Dirk Kuyt and Fernando Torres.
"Brad Friedel was outstanding," said Villa manager Martin O'Neill. "He rolled back the years. He was fantastic against his old club to perform like that at Anfield. He will be delighted with himself, and rightly so, and we are delighted with him. It was a fantastic performance from the whole side and we fully deserved the victory."
Villa scored on an own goal when Brazilian Lucas flicked Ashley Young's free kick into his own goal, Curtis Davies beat two Liverpool players to Nicky Shorey's corner kick just before halftime, and Steven Gerrard fouled Nigel Reo-Coker for a penalty kick converted by Ashley Young.
The loss was the first for Liverpool at Anfield in league play in 32 games and put more pressure on Spanish manager Rafa Benitez.
The loss was Liverpool's second in three games. The club's difficult financial situation means Benitez has little money to spend on the transfer market.