Ireland, who missed out on the World Cup after a controversial loss to France in a playoff, outplayed and outclassed Algeria in a warm up game on Friday.
They capitalized on two errors from Algeria keeper Faouzi Chaouchi and a late penalty to secure a comprehensive victory through a brace from Robbie Keane and a goal from Paul Green.
The defeat has set alarm bells ringing for Algeria ahead of the 11 June-11 July World Cup.
"Ireland are a formidable team - they were superior to us and deserve a place in the World Cup," Saadane, who was in charge of Algeria when they made their last World Cup appearance in 1986, said after the game.
"But England will be a tougher team than the one we faced tonight. They are one of my favorites to reach the final."
Algeria will begin their World Cup campaign against Slovenia on June 13 before facing England five days later.
The Desert Foxes will play the United States in their last Group C game on June 23.