Benitez's struggling squad has been ravaged by injuries in recent weeks
Boss Rafael Benitez has defended Liverpool's decision to send players to a Serbian clinic for treatment.
Glen Johnson, Fabio Aurelio, Yossi Benayoun and Albert Riera have visited Belgrade for an unusual procedure that involves massage with horse placenta.
Arsenal's Robin van Persie is also set to receive the controversial treatment after rupturing ankle ligaments.
Benitez said: "Many top players have been going for seven years, it has been successful and I believe it is safe."
The procedure appears to be paying dividends for the Liverpool manager, who has seen all four players return to full training in time to face Manchester City on Saturday in what is a massive week for the Reds.
The clinic, run by physiotherapist Mariana Kovacevicrun, has received criticism for using such a sensitive organ in medical treatment.
The placenta connects the foetus to the uterine wall in mammals. And fresh samples of the organ are rich in stem cells, which can develop into different types of tissue like muscle and bone.
We checked it out when we became aware of the different players who had been. I must admit we have been surprised with how well it has worked.
Kovacevicrun's procedure involves massaging cream into the affected area and although it is still not universally accepted in medical circles, Benitez is convinced of its merits.
"We knew of other players at Premier League clubs who have been to Belgrade for treatment with this lady," stated Benitez.
"She has been working for seven years with top-class sportsmen, not just footballers. So she has the experience.
"We felt it was a good opportunity to send some of our players. We sent two - Benayoun and Riera - and they came back and started training straight away.
"So we decided to send two more, Johnson and Aurelio, and the same thing has happened. They have been training and all four will be in the squad against City."
Several players from clubs across Europe have travelled to Belgrade to receive the treatment in recent weeks.
Arsenal allowed star striker Van Persie to head to Serbia after he was injured against Italy, while Dutch team-mate Orlando Engelaar has also been treated.
Van Persie is one of the most high-profile players to receive the treatment
And ironically it was the advice of one of Manchester City's players that led to Liverpool sending their players to Serbia in order for them to be fit to face Mark Hughes' side.
Reds midfielder Riera and City full-back Pablo Zabaleta are friends from their time together in Spain, and it was the Argentina international who told his friend about the treatment he had in Belgrade.
Benitez added: "Zabaleta told Riera about it.
"City have sent two, (Vincent) Kompany and Zabaleta beforehand, and they were playing within days.
"We checked it out when we became aware of the different players who had been there. I must admit we have been surprised with how well it has worked.
"It means we have players available and training that we expected to be out for several weeks."
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