Lyon president Jean-Michel Aulas believes his team would be on course to qualify for the Champions League knockout stages if striker Nabil Fekir had not been seriously injured.
Having lost 3-1 against Zenit St Petersburg on Tuesday, Lyon are bottom of Group H in Europe's premier club competition with just one point from their three matches so far.
Last season's Ligue 1 runners-up have also got off to a mixed start in the French top flight as they sit sixth in the standings, a full 10 points behind defending champions Paris Saint-Germain after only 10 matches.
But Aulas, 66, says things would be different had Fekir not suffered a cruciate ligament injury playing for France against Portugal last month.
The Lyon academy graduate, 22, was voted Ligue 1's Young Player of the Year last season and had scored four goals in four matches at the start of the current campaign -- including a stunning hat trick in a 4-0 win over Caen.
But Fekir is now expected to be out for six months after undergoing surgery.
"I can guarantee you that with Nabil we would be in the top three in the league and that we would have six more points in the Champions League," Aulas told L'Equipe.
Lyon spent heavily on new players over the summer including right-back Rafael, centre back Mapou Yanga-Mbiwa, central midfielder Sergi Darder, attacking midfielder Mathieu Valbuena and striker Claudio Beauvue.
While some of the latest recruits have taken time to settle in, Aulas believes that the loss of a player who scored 13 goals and made nine more in Ligue 1 last season is most significant.
"Last season, Nabil Fekir wasn't injured," he added. "Not only did we spend €40 million on new signings but we also kept all of our players.
"We didn't make any signings to the detriment of those already there. On the contrary, we extended and improved their contracts.
"But the season is long and for the moment we haven't been knocked out of anything."
He maintains that it was up to existing squad members to help new arrivals integrate, but also said rivals like Marseille and Bordeaux are experiencing similar problems.