Barcelona might have been in crisis before the start of the 2020/2021 season but the Blaugrana have had a bright start to the domestic season, having won two consecutive La Liga matches with an aggregate of 7-0.
Sevilla on the other hand started their season with wins against Cadiz and Levante.
Lopetegui explained in his pre-match press conference that Sevilla must be at their best in Catalonia when they face Koeman’s men.
"We have to be at our best; there is no other way against Barcelona," the former Spain and Real Madrid coach said.
"It's a different side with a new coach and a renewed energy, and they're showing good things.
"However, every match is an opportunity and we have to do what we want to do."
Sevilla were drawn against Chelsea, Krasnodar and Rennes in the Champions League group stage and the Spanish coach is excited about the prospect of playing in Europe’s premier club competition.
"I made an assessment at the time, it's a very difficult group," Lopetegui confirmed.
"Nothing other than that can be expected in this competition.
"Rennes are the current Ligue 1 leaders; Krasnodar are a growing team; and obviously there is nothing that needs to be said about Chelsea."