The 18-year-old midfielder showed remarkable poise to beat experienced keeper Andres Palop twice in one-on-one situations, lobbing in for the first goal after 25 minutes and dribbling past him on a breakaway for the second before halftime.
Canales was applauded by both sets of fans when substituted midway through the second period, by which time Sevilla had cut the deficit after Ndri Romaric bundled the ball in at a corner.
"We knew it was going to be tough in January but not this tough. We played a disastrous first half," Sevilla coach Manolo Jimenez told reporters.
"We are missing a lot of players but that is no excuse. We are losing games because of our own failings rather than through the merits of our rivals."
Atletico Madrid put their embarrassing midweek King's Cup first leg defeat behind them to crush Real Valladolid 4-0.
Coach Quique Sanchez Flores criticised his team's attitude after they lost 3-0 at second division strugglers Recreativo Huelva on Wednesday and they responded with a vastly improved display in Valladolid.
"I'm delighted my players have reacted and today we saw them at their best," Sanchez Flores told reporters. "We couldn't have played any worse than we have been doing."
In the late game, Villarreal were held to a 1-1 draw at home by Almeria with Corona's second-half penalty cancelling out Nilmar's 40th minute header.
