The Red Deer Rebels selected Phaneuf in the third round of the 2000 WHL Bantam Draft. One year later, he joined the Rebels for the 2001–02 season and recorded 32 points in 67 games. He added two assists in 21 games as the Rebels lost in the WHL Final against the Kootenay Ice. He improved to 3o goals and 42 points in 2002–03 as the Rebels again reached the WHL Finals, again losing, this time to the Kelowna Rockets. Phaneuf's development earned him comparisons to Hall of Famer Scott Stevens, as he was lauded by scouts for his physical style and ability to excel both defensively and offensively. Then-Calgary Flames general manager Darryl Sutter valued Phaneuf so highly in the 2003 NHL Entry Draft that he attempted to trade up from his ninth overall selection in the Draft, though to no avail. Nonetheless, he was able to select Phaneuf with Calgary's first selection in the draft.