Jurgen Klopp's front three have scored 89 goals between them this season, having led their team to the Champions League final against Real Madrid.
However, two consecutive losses against Roma and Chelsea has made Jenas question the Merseyside outfit's forward line.
"Mohamed Salah did not look that interested against Chelsea, which was odd, but I was more concerned with the way Liverpool's entire front three played at the Stadio Olimpico," Jenas wrote in an article for the BBC.
"I saw something in the second leg which I have not seen all season, which was Salah, Roberto Firmino and Sadio Mane being selfish for the first time. Usually, when they counter-attack, all three of them are trying to find each other and the best route to goal. Yes Salah has scored the majority, but they have been sharing the goals out, which is one of the reason things have worked so well. This time, it seemed like it was suddenly every man for himself at the top end of the pitch - it was like they did not want to pass to each other anymore. It was almost as if they had looked at the records books about who had scored what in the Champions League and were thinking 'I want to be the man who scores the most'.
"People have been talking about this Liverpool attack as being among the best front threes we have seen in European competition, but that is on the basis of them playing together as a unit. Yes, it is just one game where that did not happen but it has happened this week, and it was followed by another game against Chelsea where they did not link up as well as usual. I don't think it is possible for their players to get that game out of their mind, because making it there was such a huge achievement for them.
"Every single member of their squad is going to want to play in Kiev, and they have also had a situation where one of their star players has just suffered a major injury. I am sure some of them looked at what happened to Alex Oxlade-Chamberlain and thought 'I don't want that to be me'. As a player the worst thing you can do is look at a big game in isolation when it is one or two matches away and think 'should I give 100% this weekend, because I might pick up an injury and miss it?' If you do that, you inevitably play badly which sends you down a whole different road."
Liverpool will host Brighton & Hove Albion in their final Premier League game on Sunday.