GUSTAVO POYET is keen to turn Ki Sung-Yeung's loan deal into a permanent transfer with the South Korean set to keep Lee Cattermole out of Sunderland's first-choice line up for a prolonged spell.

Ki moved to Wearside on a season-long loan from Swansea City on August transfer-deadline day having tumbled down the pecking order at the Liberty Stadium following the summer arrival of Jonjo Shelvey, Jose Canas and Jonathan de Guzman, who rejoined the Swans for a second spell.

At the time, Swansea chairman Huw Jenkins publicly dismissed suggestions that Ki's loan departure would pave the way for a permanent exit, and the terms of his contract with Sunderland are not understood to include a clause for a transfer next summer.

However, with Ki having become an increasingly influential performer in recent weeks after a slow start to his Black Cats career, Poyet will urge director of football Roberto De Fanti to push for a permanent deal.

“It is still early doors (in terms of his future) and I don't know how expensive he is,” said Poyet. “But we will see. He plays the type of football that I really admire.

“He has the ability to pass the ball with just one touch and change from one side to the other, or run with the ball and have a shot with either foot.

“If he believes that he can do a bit of the work the other way, the defensive way, he is a player who can give us the lot.”

Ki cost Swansea £6m when he signed from Celtic in August 2012, a club record at the time, and it is unlikely that the Welsh club would be willing to sell him for much less than that figure.

However, his value to Sunderland's current preferred way of playing is considerable as he fills the crucial role in front of the back four.

Poyet has told his players that he wants them to adopt a patient passing style that involves playing the ball out from the back and moving through midfield rather than directing long balls towards the strikers.

In the last couple of matches, Ki has been the pivot at the base of the midfield, picking the ball up from the defenders and moving it on to his fellow midfielders.

He performed the role superbly against Manchester City and is set to continue in the same position against Stoke City on Saturday, a game that marks the end of Cattermole's three-match suspension following his dismissal at Hull.

Cattermole will be available for the trip to Aston Villa on November 30, but it is becoming increasingly difficult to see how he will dislodge Ki and win back his place in the side.

The former Middlesbrough trainee is a combative ball winner rather than a technically-gifted passer, and while Poyet will not dismiss his qualities as readily as his predecessor, Paolo Di Canio, it is clear that Ki fits the Uruguayan's preferred style much more readily.

“He (Ki) had to wait for his chance,” said Poyet. “In the beginning, it was Lee Cattermole in there and he wanted to play in that position.

“Then there was the sending off, and he (Ki) needed to come in and show the manager that he wanted the shirt. He had to make it difficult for Lee to come back. He is there at the moment, and he has the chance to stay there.”

Meanwhile, Poyet is investigating the possibility of signing his teenage son, Diego, from Charlton Athletic.

Diego is yet to start a senior game for the Addicks, but the 18-year-old has made a string of appearances for the club's development team and is regarded as an extremely promising attacking midfielder.

Despite being eligible to play for Uruguay, he has represented England at under-16 and under-17 level, and been linked with Arsenal, Liverpool and Manchester United in recent months.

He is expected to leave the Valley in either January or the summer, and his father will hope his familial link proves strong enough to persuade him to snub other offers in order to move to Sunderland.