The Light Blues host the Ligue 1 outfit in their Europa League Group A opener at Ibrox on Thursday night.
Since Gerrard took over as Gers manager in 2018, he has garnered a record of 25 wins, 16 draws and eight defeats against European opposition and rates French side Lyon, bossed by Peter Bosz, who guided Bayer Leverkusen to victory over the Scottish Champions in the last-16 of the Europa League in 2020, as top class.
"They are arguably the best," said Gerrard, who confirmed that defender Filip Helander has had surgery on a knee problem which will keep him out for "the foreseeable future" and that centre-back Connor Goldson is available again after Covid-19 isolation.
"At full strength Lyon are very much a Champions League team with Champions League-calibre players, they have a manager who got this job on the back of doing ever so well as the Bayer Leverkusen manager.
"He has been here before, he knows what we are about so this is a real big test tomorrow and there is no doubt about it we have to be at our best and that goes for both sides of the game.
"We have to have a high level of focus and concentration tomorrow because if you don't against these teams you can be punished and punished very quickly so it is a real good test and challenge.
"But we have to have our own confidence and belief that we can play at this level, we can compete and at the right times during the game we have to show bravery that we can hurt the opposition as well.
"We are excited, we are looking forward to it but we know the size of the challenge and it is arguably the biggest we have had as a group."
Gerrard is reading little into the news that Lyon captain Moussa Dembele, the former Celtic striker, will not travel through injury.
He said: "I think this club and this team knows more than most the abilities and quality that he possesses.
"He has obviously started reasonably well and he has gone to Lyon and built on his career at Celtic, gone to the next step into one of the top-five leagues in the world and produced so I have a lot of respect for the player in terms of his technical quality and ability.
"But I don't really get involved in opinions of whether Lyon will be weaker or stronger because they have players capable of coming in, they have talent all over the pitch, especially in the front-four positions.
"So it would be very naive for me to think Lyon are going to be any weaker just because one player is missing."
Helander was stretchered off in the second half of the cinch Premiership match against St Johnstone at McDiarmid Park on Saturday after pulling up.
Gerrard said: "Filip will be missing, he has had surgery in the last 24/48 hours to fix an issue that they spotted when they went inside to have a look so he will be missing for the foreseeable future.
"He is a big player for us, he has always been consistent so he will be a miss and a loss but again it is the reason why it is always important to have four centre backs so you can cope when one is missing.
"In terms of how long he will be out for, it is difficult to put a time frame but he will certainly be missing for at least a few months."