SIR BOBBY ROBSON has challenged Steve Caldwell to cement a future for himself with Newcastle United - and save the club millions.

The 22-year-old Scottish international has displaced the experienced Nikos Dabizas at centre-back as manager Robson looks to reshape his rearguard.

Newcastle have been linked with a string of defensive targets, most notably Lazio's former Manchester United linchpin Jaap Stam.

Robson has even consulted Old Trafford counterpart Sir Alex Ferguson about 30-year-old Stam.

But the situation is complicated by the fact that crisis-torn Lazio still owe Manchester United around three-quarters of the £16.5m fee they agreed for Stam early last season - and the big Dutchman insists he wants to stay in Italy.

Robson is resigned to missing out on Stam, who says he would favour a move to either Juventus, Internazionale or AC Milan if Lazio are forced to cash in.

The Magpies' boss refuses to rule out a New Year swoop to strengthen his backline, but yesterday threw down the gauntlet to Caldwell and Co.

Stirling-born Caldwell is out of contract at the end of the season and is still awaiting the offer of a revised deal.

He said: "I don't know why I haven't been offered a contract, but it's still my dream to play for this club.''

And Robson declared: "The most important players are those who are already here.

"We're looking at the transfer scene. The acquisition of the top players we would like is not easy. We keep trying, but they are not available.

"You can understand it because we wouldn't want to sell people like Craig Bellamy, Aaron Hughes or Andy Griffin, unless it was for crazy money.

"But those days have gone now and maybe that's a fine thing. We don't want to spend money, but we will if it's necessary.

"At the same time, I haven't forgotten about Dabizas, who's still a good, solid player and a bit unlucky to be out of the side.

"Steve Caldwell has come in and done well and not given me any reason why he should go out of the side.

"But we still need to look at him a bit longer to ensure he is what we need. He might be one of the answers.

"But we also have Hughes, Andy O'Brien, Dabizas and Titus Bramble.''

England Under-21 defender Bramble was yesterday due to resume training after suffering a setback with the hamstring injury which has kept him out for almost two months.

And the versatile Olivier Bernard was also back with the rest of the squad following the knee problem he picked up in the 3-1 Champions League defeat in Barcelona nearly a fortnight ago.

Robson said: "Thursday's game at Bolton might come too soon for Olivier, but Tottenham here on Sunday could be a possibility. Titus has just had a slight reaction to his hamstring.''

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