The appearance of David N'Gog last Tuesday as a second half substitute was a surprising one, yet it says much about the quality of Liverpool's squad.

In explaining the substitution, Rafael Benitez said that he wanted to change things up front, to put on a striker who could perhaps add something different. Nothing wrong with that yet when that something different is a nineteen year old with one substitute appearance to his name, it is unlikely that much will change.

It isn't simply striking alternaties that Benitez lacks. Players in other areas have struggled to prove their worth: in theory Yossi Benayoun is a valid alternative in midfield yet lately he has struggled to make an impact when given the chance. The same applies, although to different degrees and for varying reasons, to Ryan Babel and Jermaine Pennant.

Elsewhere, Andrea Dossena has admitted that he has found settling at Liverpool hard whilst Philip Degen has barely been seen.

It is only Sami Hyppia and Lucas Leiv who offer a fair degree of reliabiity even though the latter's inclusion here won't sit well with many fans.

Even so, Benitez is increasingly being faced with a situation where if the regulars fail to do the job then he has no real alternatives.

Of course, squad players are just that: players whoc can't be considered as being as good as the regular starters. Yet their value in the modern game is immense. And it is where Liverpool struggle most when compared to Chelsea and, in particular, Manchester United.

What's worse, ultimately it could have a telling effect on any possible title challenge