The Magpies booked a last-16 clash with Anzhi Makhachkala by beating Metalist Kharkiv 1-0 in the Ukraine on Thursday night - but Pardew knows his men must refocus quickly.
He said: "We have got two very important Premier League games and if we could get three, four points out of those two games, I would take that now.
"It would give us a good angle to go into the next phase of the Europa League."
Pardew left Southampton in 2010 following a rift with club chairman Nicola Cortese, and admits the game carries a special meaning for him.
He added: "It's going to be dear to my heart to win this game, trust me, so I won't be pulling any punches in my dressing room.
"But that's easier said than done. Southampton have definitely picked up and they play a high pressing game which we are going to have to combat.
"He [new Saints boss Mauricio Pochettino] has had a good start. There are some good players there and I am looking forward to seeing them.
"They got the result over us the last time and they thoroughly deserved it, so we need to perform a lot better than we did at their place."