MYSTERY surrounding Robert Huth's ankle injury means Middlesbrough are even more determined to retain the services of Chris Riggott next month.

Riggott, arguably Boro's most consistent performer last season, has worked his way back to fitness after four months out and has fallen behind in the selection stakes.

The acquisitions of both Jonathan Woodgate and Huth, coupled with the outstanding displays from Emanuel Pogatetz at the heart of the defence, means Riggott is now effectively fourth choice.

It has alerted a couple of clubs to his lack of first team action and Newcastle United, looking to bolster their defensive ranks, are monitoring the situation.

But Middlesbrough boss Gareth Southgate, a former backline partner of Riggott, does not want to lose the services of the former Derby man, particularly with no date set for a Huth return.

"We don't know how long Robert will be out for," said Southgate. "Jonathan and Emanuel have been outstanding so he has fallen down the pecking order while he has been injured.

"Chris has a lot of experience and was outstanding last season. He is not someone I want to lose. The first time he was available was the week before Fulham.

"He may not have played games but he has only missed, through selection, one game. All Chris can do is wait for a chance. When that comes he has to play at the same level Emanuel has been and he will stay in the side.

"Chris had a very good season last season. We need a strong squad and we need competition for places."

Huth has not played since suffering ankle ligament damage in training after the defeat to Tottenham on December 5.

But, despite the lay-off, the club's medical staff have been unable to determine the extent of the damage caused.

Southgate is having to decide when the best time will be for the German to test out the problem, rather than keep him sidelined indefinitely.

The Middlesbrough boss admits it will be at least three weeks, possibly many more, before he makes a Premiership comeback.

"Robert's problem is a strange one," said Southgate. "With modern technology scans tell you to the day when they are back.

"But his is inconclusive and we have to see how he progresses. We will see how he reacts, but it could be two to three weeks. He is doing light training now and it's very difficult to put a timescale on it."