JACKIE McNamara will be presented as the new manager of Dundee United today and will then immediately begin preparing his team for their biggest game of the season so far, against Rangers in the William Hill Scottish Cup on Saturday.

McNamara is expected to sign a two-and-a-half year contract after United agreed compensation with Partick Thistle to take him to Tannadice as Peter Houston's successor. The appointment of the 39-year-old means one in four of the Clydesdale Bank Premier League's of managers are in their 30s.

Steven Pressley, the Falkirk manager, and the former United striker Billy Dodds were also interviewed by three members of the Tannadice board of directors. Pressley had been the favourite for the job, but it was decided to go with McNamara and he will attend a media conference at Tannadice today.

His assistant at Firhill, Simon Donnelly, will follow him to Tayside to fill the same role. McNamara became manager at Thistle on a caretaker basis when Ian McCall left in April 2011, and was then appointed on a one-year rolling contract. Thistle finished sixth in the first division last season, McNamara's first full campaign in management, but have been more consistent this term and are currently second, five points behind leaders Morton with two games in hand. Losing their impressive young manager was a major blow yesterday as Partick strive to return to the top flight for the first time since 2004. The Alloa Athletic manager, Paul Hartley, was immediately linked with the vacant Thistle job last night.

Houston announced a fortnight ago that he would leave when his United contract expired at the end of the season, having declined to accept the terms of a new offer. However, Stephen Thompson, the Tannadice chairman, was dissatisfied with that arrangement and accelerated Houston's departure and he left on Monday.

Houston had claimed budget cuts were being imposed on United's playing department which will make it difficult for the club to remain competitive next season, but McNamara had no qualms about that in his meeting with their directors.

The former Celtic players will take over in the build-up to the club's most high-profile game of the season so far, the Scottish Cup fifth-round tie at Tannadice. Rangers have backed a boycott of the match by their supporters – over United's involvement in the vote which prevented Charles Green's newco regime being admitted to the SPL last summer – although around 200 visiting supporters will be there. The animosity between the clubs has given the tie heightened significance.

McNamara had a distinguished playing career with Dunfermline, Celtic, Wolves, Aberdeen, Falkirk and Thistle. At Parkhead, he played under Tommy Burns, Wim Jansen, Jo Venglos, John Barnes, Kenny Dalglish and Martin O'Neill and won three league championships, three Scottish Cups and three League Cups. He earned 33 Scotland caps.

Thistle last night issued a statement which simply said: "Following an approach from Dundee United, the board of directors of Partick Thistle FC have reluctantly granted permission for Jackie McNamara and Simon Donnelly to speak to them about their vacant managerial position."