Rome - Roma icon Francesco Totti admits his side could face an uphill struggle on their return to European competition as Italian clubs have fallen behind their continental rivals in recent years.
Roma will end a four-year wait to compete in the Champions League when they host CSKA Moscow in the Italian capital on Wednesday.
The Giallorossi last competed in Europe's premier club competition in the 2010/2011 season.
Totti, who has completed 20 seasons for Roma, said: "In previous years we had Juventus, Milan and Inter's treble (in 2010), but we've stopped doing well in Europe.
"The anwer is simple - teams like Real Madrid, Barcelona and Bayern Munich have just become a lot stronger."
Asked if Roma were ready to face Bayern Munich and Manchester City in Group E, he added: "The group matches will reveal whether we're ready for this competition or not. We're facing strong teams, it will be difficult."
Totti, 37, is expected to start alongside Ivory Coast striker Gervinho and forward Juan Iturbe as Roma look to collect a precious three points ahead of likely sterner tests in the group.
Coach Rudi Garcia said he has plenty of confidence in his side following successive wins over Fiorentina (2-0) and Empoli (1-0), but the Frenchman warned of CSKA's condition. The Russian league started almost two months ago.
"We've already shown, especially against Fiorentina, how strong we are at holding up the ball and waiting to fully exploit space if we manage to draw the other team out of their half," said Garcia.
"But CSKA are far from being the weakest side in the group. They've played eight games already and we've only played twice. "So the advantage is all theirs.
"We have to watch out because they're strong on the counter-attack. But I have confidence in my team."
CSKA, the 2005 UEFA Cup winners, will be without several players due to injury and suspension. Defender Georgi Schennikov, midfielder Rasmus Elm and forward Vitinho are all sidelined through injury, while halfback Aleksandrs Cauna remains a fitness doubt.
Russian international Alan Dzagoev and Swede Pontus Wernbloom will also sit out the first of respective three-match bans after being sent-off last season against Czech side Viktoria Plzen.
Totti, meanwhile, laughed off questions about his possible retirement.
"The years go by but I really don't feel it. I still believe I have a lot to offer and I hope to keep contributing to the team," said the Italian, who was left at home for Italy's ill-fated World Cup campaign this summer.
"I've already said that when I no longer feel strong I will be the first person to say."