Arsene Wenger feels more than a tinge of regret that England defender Matthew Upson did not stay and fulfil his potential at Arsenal - and he even thought about buying him back.

The 30-year-old centre-back, who joined the Gunners from Luton in 1997 in a £2million deal, is set to face his old club at Upton Park on Sunday.

With the likes of then captain Tony Adams, Steve Bould and Martin Keown all ahead of him at Highbury, Upson found his chances limited before suffering a serious knee injury which kept him out for the best part of a year.

Loan spells at Nottingham Forest and Crystal Palace followed, with Upson eventually making 22 first-team appearances for Arsenal during 2001/02 - which saw him collect a championship winners' medal.

However he broke his leg during February as the Gunners went on to complete the double.

With Sol Campbell and Kolo Toure the established defensive partnership, Upson moved on to Birmingham in January 2003.

Now settled at West Ham, after a £6million switch two-and-a-half years ago, Upson has become a regular in Fabio Capello's England squad and looks set to head to the World Cup next summer.

Wenger said: "I knew when he left that he would make a big career, but at that moment when Matthew was here, he was impatient.

"That I could understand as well because I bought him at Luton and after a few years he didn't play here.

"I didn't stop him [going] because I knew he had qualities to play in the Premiership, but he had players in front of him that stopped him."

Wenger insisted: "I knew he would make it.

"He had Premiership quality and had the potential to be international quality.

"He is there now because he is at the right age for a central defender and for a few years now he has not been stopped by injury which was his problem for a while."

Wenger revealed Upson was a player he had contemplated trying to bring back to Arsenal before he switched to Upton Park.

"Yes, he was always in my mind. Upson has good quality, good attitude, good spirit," said the French coach.

"But of course this is not the best moment to talk about that because he is a player at West Ham.

"Three, four, five years ago yes, but now he is settled and has a good career where he is."

Upson is not the first, and highly unlikely to be the last, youngster Wenger brings through at Arsenal.

However, the Gunners boss accepts sometimes they cannot always make the grade in your side.

"Between the age 18 to 21 is a very sensitive step for a player," Wenger observed.

"You have to make the step. If you don't make it you become impatient and you lose the players."

Wenger turned 60 yesterday, but the burning desire to succeed shows no signs of fading.

"Am I happy with all that I have achieved? Certainly not. I expect always more and you can never be completely happy with what you do," he said.

"I have helped to develop the club and gave some great moments of happiness to people who love football and to our fans as well.

"I have had a positive influence on the career of the players and have respected my duties of this club."

Wenger added: "The only credit that I give to myself is that I work very hard my whole career and always try to improve.

"You always think you could have achieved more and make better decisions."