Gretna's Grainger Tannadice bound

Grainger has been with Gretna for more than five years

Dundee United have agreed a deal to sign 21-year-old Gretna defender Danny Grainger when the January transfer window opens next week.

The Carlisle-born left-back will move to Tannadice on Tuesday and end his five-year stay with Gretna.

Grainger joined on schoolboy terms and helped Gretna climb through the Scottish Football League and into the Clydesdale Bank Premier League.

He has made 10 appearances in the Scottish Premier League.

But Grainger, who was on loan to Brechin City during 2006, will not be involved in Saturday's match away to leaders Celtic.

United manager Craig Levein used midfielder Willo Flood at right-back and switched Sean Dillon to the left for their Boxing Day defeat by the Glasgow outfit.

Until the first of January, when we can bring some players in, we continue to struggle in a couple of areas Dundee United manager Craig Levein

Flood had replaced Stuart Duff, who paid for an error that gifted Gretna a goal in the weekend defeat to the side sitting bottom of the table.

Levein was happy with how the Irishman performed at the back against Celtic and stressed that his hands were tied until the transfer window opened.

"I felt that last week we defended exceptionally well against Gretna but gave away goals through individual errors," said Levein.

"If that happens, it can be something that spreads throughout the team, so I thought it was important we made a change.

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"I thought Willo was fairly good. He didn't beat Jiri Jarosik that often in the air, but he played the position very well.

"He covered his centre-backs and got forward when he could.

"Until the first of January, when we can bring some players in, we continue to struggle in a couple of areas.

"The full-back area is one of them and we are still light up front."

Berwick Rangers midfielder Danny Swanson will become a United player on 1 January, while Levein has also been linked with Leicester's teenage striker Eric Odhiambo.