Les Gones have made a strong start to their Ligue 1 campaign, claiming four wins from five games, but take a step into the unknown in Group I against last season's Gambrinus Liga runners-up.
And Gonalons said at a press conference reported on Lyon's website: "They are a team we do not know too well. We will watch them on video.
"They have a lot of experience in Europe and we have to prepare well to face up to them. It will not be easy."
The two teams met in the Champions League group stage in 2004, with Lyon winning both games.
Gonalons, who at that time was a member of the club's youth set-up, has fond memories of the comfortable win at the Stade Gerland.
"I was in the stands for the 5-0 win," he said.
"Several players from the youth team played and it was a great party."
Experienced full-back Anthony Reveillere is the only remaining OL player from the team that put five goals past Sparta eight years ago.
Michel Bastos, who along with Bafetimbi Gomis leads Lyon's scoring charts with three goals already this season, misses out due to injury but Sparta coach Vitezslav Lavicka knows his men will still be facing high-class opposition.
He said: "The Lyon team will be very strong even without Bastos, who could be replaced by (Alexandre) Lacazette.
"We are not afraid of them, but we respect this team.
"Hopefully we can get a very good result on Thursday evening and represent Czech football."
Marek Matejovsky is back in contention for a place in the Czech side's midfield, to the relief of Lavicka.
"We have really missed Matejovsky," he said. "He has trained and he will either be in the starting line-up or among the substitutes."