Goalkeeper Pepe Reina claims the departure of Javier Mascherano is a "big problem" for Liverpool.
Argentina captain Mascherano left for Barcelona last month after telling new Reds boss Roy Hodgson of his desire to move on after three and a half years at Anfield.
Hodgson banked £17million from the sale and signed Christian Poulsen and Raul Meireles in a bid to bolster his midfield options.
However, Spain goalkeeper Reina is concerned at the departure of the combative South American.
"The departure of Mascherano is a big problem for Liverpool because he is one of the best players of his type on the pitch," he said in the Daily Mirror.
"Javier is very competitive, very Argentinian and he always offers his maximum in every game.
"For Barca this is a good new thing, but it's not for us.
"Mascherano will be a positive surprise in La Liga. He is a footballer who works, works and works.
"Also, personally, he is a good character. He is quiet but very friendly."