This is where I disagree with most of the posters here. I think an attacking midfielder/winger is MUCH more of a priority for us than a CM/DM. I really don't get all the people who think a M'Villa or Wanyama would improve us so much. Lucas might not be the best DM in the world, but he is not that bad really and far from our main problem. I'm not at all sure M'Villa is a better player than Lucas right now (his team is currently 11th out of 16 in Russian Premier league and I didn't hear any particular plaudits about his performance from pundits or fans), but even if he were, for the team as a whole it would be a marginal gain at best.
I think a quality attacker like Mkhitaryan or Konoplyanka or, in this case, Salah would improve us much more. People say we are ok on the wings but lacking in CM – but right now the fact of the matter is that we have a CM (Henderson) playing on the wings – he has started every single game and has a grand total of 1 goal and 1 assist in all competitions to show for it. We also have Moses, who is talented but doesn't work hard enough on the pitch to be a starter for Rodgers, Aspas who didn't settle well and a couple of talented and raw kids. Combined, all of our "attacking midfield" players have 4 goals and 3 assists in all competitions – a really paltry return with the season approaching the half-point.
I think that's a big problem, especially now that our second-best striker (Sturridge) and our top assist man (Gerrard) are both out until late January. Who is going to replace them? If you could pick any player in the world to make our team stronger, do you really think a Mascherano who replaces Lucas would make more of a difference than, say a Ribery who replaces Sterling, Henderson or Moses? If we had a really fearsome attacker to complement Suarez and Coutinho, teams would be afraid to cross halfway line when playing us and Allen, Henderson and Lucas (+ Gerrard when he is back) would manage CM between them with no problems.