The result of Dundee United defender Frederic Frans’ visit to a specialist to discover the extent of the groin injury he suffered at Falkirk last weekend has brought bad news.
Frans was carried off midway through the first half of the draw at the Bairns and missed Tuesday’s cup win over ICT.
Now it’s been confirmed the Belgian has torn the muscle and will be absent for up to six weeks.
Midfielder Calum Butcher will also have to sit out the quarter-final as he serves the second of a two-match ban for his red card in the last round at St Mirren.
Peter Pawlett got his marching orders in Tuesday’s game but the forward will be available for the weekend before missing the league trip to Partick Thistle on Saturday week.
The aim on Sunday is to keep 11 men on the park for the entire 90 minutes but Robbie admits he has been happy with the way his players have coped when reduced to 10 men.
“It is something we work on at times and it’s hard to break down, two banks of four,” he said.
“Your wide players get back in and your centre players don’t move, which they did on Tuesday and I thought they saw it out pretty comfortably.
“There was a nervousness, which is understandable but they did it.”
Fans heading to Tannadice for the cup clash are reminded they can get tickets in advance for a reduced price of £15. Turnstiles will be in use but the pay-at-the-gate price will be £20.
Sunday is also Alzheimer’s Awareness Day at Tannadice and bucket collections will be taking place in and around the stadium.