Ziege appears out of favour with boss Gerard Houllier with England international Jamie Carragher the first-choice left-back and young Frenchman Gregory Vignal pushing through the ranks.
Despite that, Ziege is still a regular with Germany, has won 57 caps and played in their recent World Cup qualifying matches against Finland and Albania.
Ziege has had spells with Bayern Munich and AC Milan earlier in his career before arriving in England with Middlesbrough.
Glenn revealed: “I would envisage another two players coming in.
“We have made a bid for Christian but he is away on holiday so it is difficult to say too much about that.
“We have spoken to Liverpool and whether we can take it on further remains to be seen in the coming weeks.”
Glenn Hoddle has admitted he’s on the trail of Liverpool defender Christian Ziege.