Shiels has much managerial experience in Northern Ireland
Ulsterman Kenny Shiels has quit his job as Tranmere Rovers' head of youth to become assistant manager to Mixu Paatelainen at Kilmarnock.
Shiels has spent three years with the League One club and was previously manager of Coleraine, Ballymena, Larne and Carrick Rangers.
He also led the Northern Ireland Under-17 side to the European finals.
Shiels told Tranmere's website: "I'm sad to be leaving Tranmere, but this is a really exciting opportunity for me."
He had left his post as Northern Ireland youth coach to join the League One club in May 2007 as their head of youth and centre of excellence.
Kenny is a Uefa Pro Licence holder and will bring an array of knowledge to the club
Kilmarnock FC statement
"It was a hard decision to leave Tranmere as it's a club you fall in love with," said Shiels. "I like to think I've made a positive impact on the future of the club through my work with the centre of excellence and hopefully the results will be seen over the next few years in the first team."
Now he will team up with former Hibernian, Cowdenbeath and Turun Palloseura manager Paatelainen, who was appointed by Kilmarnock last week.
Paatelainen was appointed Killie manager last week
The Scottish Premier League club's website stated: "Kenny is a Uefa Pro Licence holder and will bring an array of knowledge to the club."
Tranmere manager Les Parry wished him well in his new role.
"I'm really sorry to see Kenny leave the club, but this is too good an opportunity for him to turn down," he said.
"I will be sitting down with the board of directors to discuss the staffing structure in the near future."
Chief executive Mick Horton said that Tranmere "cannot stand in the way of this move" and thanked Shiels for his work with his club.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.