Glen Johnson, Fabio Aurelio, Yossi Benayoun and Albert Riera have all visited the Belgrade clinic run by physiotherapist Mariana Kovacevic, having previous been ruled out for up to a month with calf and hamstring injuries. The unusual treatment involves massage with placenta.

All four have returned to full training and are in line for Saturday's vital home Premier League clash with Manchester City, with a Champions League trip to Hungary to face Debrecen on Tuesday and the Merseyside derby at Everton next Sunday.

Boss Benitez is desperate to salvage Liverpool's season and get them into the Champions League again next year, and he was prepared to try almost anything to get his top stars fit.

With Steven Gerrard also certain of starting the match against City follow recovery from a groin problem, it is only striker Fernando Torres (also groin) who is not available against Mark Hughes' men.

And it is City who may have inadvertently alerted Liverpool to the placenta cell treatment available in Belgrade.

Riera and City full-back Pablo Zabaleta were friends and team-mates from their time together in Spain, and it was the Argentina international who told his friend about the treatment he had in Belgrade.

Benitez said: "We knew of other players at Premier League clubs who have been to Belgrade for treatment with this lady, and we were made aware that it was very effective. Zabaleta told Riera about it.

"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.

"Arsenal's Robin van Persie went earlier, but now there are several more top players who are going to have treatment in the same way.

"City have sent two, (Vincent) Kompany and Zabaleta beforehand, and they were playing within days.

"There have been no injections, it is a placenta cream applied with a (massage) machine that creates waves of pressure."

He added: "We sent our players, and Van Persie was there. Kompany and Zabaleta have also been there, and we have been made aware of the success of this treatment over several years.

"Many top players have been going there for seven years, it has been successful and I believe it is safe.

"It is good for specific injuries, doctors have explained the treatment and the components of the cream that is used. We are happy with it.

"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. Can we guarantee that they are fully fit? We will see, but they have trained with the rest of the team for three days and they are OK."