Hi,
SelectionUnit="Cell" IsSynchronizedWithCurrentItem="True"
Set the above properties for DataGrid and in the code behind do the following changes.
DataGridCellInfo info = new DataGridCellInfo(this.dataGrid.Items[2], this.dataGrid.Columns[1]);
this.dataGrid.CurrentCell = info;
this.dataGrid.SelectedCells.Clear();
this.dataGrid.BeginEdit();
this.dataGrid.CommitEdit();
this.dataGrid.CurrentItem = info.Item;
this.dataGrid.SelectedCells.Add(info);
Hope it helps.
Regards,
Kannan. S