In their absences, midfielder Jordan Henderson had spent much of the campaign as a placeholder in defence, but the club captain was forced to undergo groin surgery at the end of February.
All four players are progressing well in their fights for fitness, however, according to their coach.
“They all are [on track],” Klopp told Liverpool’s official website.
“Joe is outside running now and all these kind of things, which is obviously always a big step after all injuries.
“He looks fine when he is running, no real reaction in the knee, which is very important. It obviously still takes time, but he’s in a good way – like Virg, Joel and Hendo.”
To Klopp’s relief, the Premier League champions have no fresh injury worries ahead of their trip to Leeds on Monday.
“No, nothing,” Klopp said. “No new ones.
“I only thought [about the question] because usually I always have some.”
Liverpool are sixth in the top flight heading into their meeting with Leeds, three points behind fourth-placed West Ham with a game in hand.
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