The Senegal attacker has missed seven matches for the Reds since he began competing in the continental tournament, and in his absence Jurgen Klopp’s men have won just one game: an FA Cup replay against Plymouth Argyle.
As well as losing to Southampton twice to miss out on a place in the EFL Cup final, the Anfield outfit have drawn with Manchester United and lost to Swansea in the league, while they suffered a 2-1 FA Cup loss at the hands of Wolverhampton Wanderers on Saturday.
Mane has been the star of the show for Liverpool, with nine goals and four assists in 19 Premier League matches and, after seeing them fall 10 points behind league-leaders Chelsea, Ferdinand feels some key weaknesses have been exploited in the absence of their most decisive player.
“Liverpool are missing Sadio Mane, his vital unpredictability, running in behind and with pace, and haven’t won since he went to the Africa Cup of Nations,” the former Manchester United defender wrote in the Sunday Times.
“It’s shown where their problem lies, the difference between Liverpool’s squad and the title winners I played for: a lack of depth.
“When your main men aren’t there, or aren’t firing, you need others to pick up the mantle. Chelsea? When Diego Costa missed a game their left-back even stepped forward and scored. Liverpool haven’t had that.
“Now is the time for the likes of Divock Origi and Daniel Sturridge to grab the bull by the horns, come to the fore and say: 'This is what I can do.' Mane’s absence was a big moment for both those players and so far they’ve disappointed.”
Daniel Sturridge has been limited to just 13 appearances in the Premier League this season, starting just five times and scoring two goals. Injuries have consistently hindered the England international over recent years, but Ferdinand feels he must prove his worth in his side’s title challenge.
“We’ve been talking about Sturridge for a long time in terms of talent and he’s come in for some stick in recent weeks, so now is the time to show his mettle, show his heart, and go out and show what he’s made of," said Ferdinand.
“I see another flaw in their squad — there’s not much experience in terms of winning. Only James Milner, Sturridge and Emre Can have won big leagues — and Sturridge and Can were youngsters who made just a few appearances for Chelsea and Bayern Munich’s title- winning teams respectively.
“They have a lot of youth and vibrant talents but…they need to start investing in winners.
“I totally believe in Jurgen Klopp. He is a manager I would love to have played for. Defensively, I see weakness. Dejan Lovren makes mistakes and Milner is not a natural full-back.
"They are not sure about the goalkeeper, and I don’t see much protection: if Liverpool don’t win the ball early you can get onto their back four quite easily.”
Klopp's host Chelsea on Tuesday in a crucial Premier League encounter as they look to chip away at the gap between them, and Ferdinand feels it could prove decisive.
"There are ways of getting at Chelsea. There’s space behind their wing-backs. But they have the know-how to get a result at Anfield. If Liverpool don’t win, they’re out of the title race — though in reality I see Arsenal and Tottenham as the only clubs capable of overhauling Chelsea."