The 31-year-old Australia striker is currently enjoying a break with his family in the southern hemisphere before meeting up with his international squad for the Asian Cup.

However, he left Teesside without giving Southgate an answer over a contract extension which has been on the table for some time, and with just weeks of his existing deal still to run.

The manager, backed by chairman Steve Gibson and chief executive Keith Lamb, has left the former Leeds frontman in little doubt as to his desire to see him remain at the Riverside Stadium.

However, having spoken to him in the last few days, he knows he will have to remain patient a little longer.

Southgate said: "He is still waiting to see everything that's there, I suppose. There is no advantage, from his point of view, to making a decision now as opposed to a fortnight's time.

"Obviously for us, it would be handy to know so we can plan and do things, but he wants to move at his own pace."

A posse of Barclays Premiership clubs, including derby rivals Newcastle, are thought to be monitoring Viduka's situation, while there has also been interest from Italian side Genoa.

However, while Southgate insists he will not force a decision, he claims he cannot make major decisions over his rebuilding plans until his 19-goal leading scorer reveals his hand.

Asked to what extent that decision would shape his transfer dealings, he said: "A huge extent because we would have to bring in a replacement - and you are not going to find the same type of player or character, so it does have a big impact on everything we want to do.

"The whole budget is geared around do we need to buy someone to go up front, or are we going to have Mark and use that money elsewhere?

"It does hamstring us a little bit but, by the same token, we have got to try to move on other things at the same time."

Having sealed a permanent move for England defender Jonathan Woodgate from Real Madrid, Boro have already spent £7million and, with Viduka out of contract, he would command no fee if he left.

Southgate's budget is limited - and he knows he may reluctantly have to sell to fund his blueprint - but he is already looking at alternatives.

Arsenal's Jeremie Aliadiere is once again understood to be in Boro's sights, while the manager expressed an interest in Crewe's Luke Varney before relegated Charlton snapped him up for an initial £2million yesterday.

Southgate said: "I have [targets], but not clear-cut and not to the point where we have bids on the table for people. That could end up being a futile exercise.

"We are losing Malcolm Christie, so we need a striker anyway, but it is whether you need somebody to go straight in, or somebody who might be a bit more developmental.

"I was interested in Varney at Crewe - if we keep Mark, it would have been good to have had a young one coming through - but Charlton have been able to move and do that.

"I would like to get to the point as a club where we can bring people in like Tottenham have done and let them develop with us, and hopefully they come through into your first team in a couple of years' time."