Everton manager David Moyes believes Arsenal are benefiting from the years of Mikel Arteta's development spent under his guidance.
The Spaniard left Goodison Park for the Gunners in a £10m deal on the final day of the summer transfer window last year after six years playing for the Scot.
Moyes admits when he first brought in Arteta from Real Sociedad, after a two-year spell with Rangers, he was unsure how well he would fare. However, he now sees Arteta as a key player and one of the leaders in Arsene Wenger's side, the visitors tonight.
"I'm not surprised. He is a very gifted footballer, he is a great lad to work with," said Moyes. "I think the manager (Wenger) was probably surprised what he offers: he is a great professional, a really good footballer and I'll be delighted to see him back – just disappointed it is in an Arsenal jersey.
"I see Mikel now and when they are having a bit of a huddle he is the one who is the leader and I think they look to him, he has taken on a lot of the leadership qualities in that side.
"He was part of the rebuilding process that had to take place at Everton when we tried to develop the team and move it on.
"We were a bit unsure when he first came here. He was a bit lightweight to play in the middle and so we played him off the side and he was great there for us, he really was.
"Eventually he moved on to be a real key figure in that period and was a big part of us developing and moving Everton forward."