Betis had no trouble swatting aside Czech minnows Jablonec in a midweek Europa League tie, but they have struggled domestically so far this season.
After two games, Pepe Mel's team are yet to get a point on the board, leading some to suggest that the team are on course for a difficult campaign.
But Real Madrid needed an 86th-minute winner from Isco to see Betis off on the opening weekend, and they lost to Celta Vigo by one goal last weekend so Pizzi thinks it would be folly to underestimate the Seville team when they arrive in Catalonia on Sunday afternoon.
"They haven't managed to score any points yet, but that doesn't mean anything," Pizzi said.
"They have a lot of quality and I am sure that they are desperate to get that first win."
Pizzi signed for Espanyol on loan from Benfica in the summer and he has slotted straight in to Javier Aguirre's side, who have started the season well.
The Catalonians fought back from 2-0 down to earn a point at Celta Vigo on the opening day of the campaign and last week they stunned Valencia 3-1 at the Cornella.
With difficult games on the horizon, Pizzi hopes he and his team-mates can maintain their good start to the campaign in the coming weeks.
"We want to keep this good spell going because getting three points is encouraging for us," he said.
"Myself, I felt a few little injury niggles in my first game, but I felt good against Valencia.
"Now I'm near to my top level and I'm happy that I am helping my team-mates here."
Veteran Spain defender Joan Capdevila will be missing for Espanyol this weekend because of a foot injury.
Betis have injury problems of their own, with forward Ruben Castro likely to be out for several weeks because of a problem with his right foot, but Brazilian defender Paulao is nearing full fitness.