The Catalans have taken seven points from the last nine to move within a point of exiting La Liga's bottom three but Pochettino is still looking for more from his side in attacking areas.
He told Marca: "We have found a solidity in defence, but we lack freshness in attack. We need more penetration and to finish our attacks. On the creative side we are good, but in the last 20-25 metres we need to be more aggressive.
"It will be a very difficult game because it is against an uncomfortable rival who brings out the worst in all their opponents. They have a lot of people in the centre of the field and we know it is a clash in which we will suffer. We have to equal what they have in force and aggression, but also develop our football."
Juan Forlin and Victor Sanchez return from suspension for the hosts, but Mubarak Wakaso is banned so Simao Sabrosa may be handed a rare start on the wing.
Osasuna are in even deeper trouble than their opponents this weekend as they sit rooted to the foot of the table with just one win from the opening 10 games but coach Jose Luis Mendilibar believes his side can use Espanyol as an example of how to get out of trouble.
He told the club's website: "We are thinking about the game against Espanyol and we can use them as an example as after the last three or four weeks they have left the bottom of the table."
The visitors though will have to cope without a number of key players through injury, including captain Patxi Punal, but Mendilibar denied he had overused the 37-year-old in recent weeks.
"He didn't get injured due to his age, nor the number of minutes played in three consecutive games," he said.
"We have a few injuries, but with the players that we have we are working to prepare for the match."