After a very poor start to their Top 14 season, Perpignan now find themselves within one point off the top four following their resounding 45-7 home win over Albi.
The return of World Cup winner Percy Montgomery after a knee injury proved crucial as the South African full back notched 23 points.
Perpignan were still missing their captain and England international prop Perry Freshwater, who failed a fitness test on his injured shoulder. But the influential Freshwater is expected to be fit for the quarter-final at London Irish on Saturday, 5 April.
USAP also had to play without two other players they had hoped to welcome back after injury, Patrick Burger and Steve Meyer, but Scottish scrum half Chris Cusiter managed to play for 67 minutes after shrugging off a calf injury.
"Things have clicked into place and we are getting some real momentum behind us," was the verdict of Springbok legend Montgomery.
"We have a big game this weekend against Bourgoin and then the London Irish game. You have to treat it like a final and we are determined not to come away from Reading with any regrets."