The last round of the competition saw the Tangerines have to battle with 10 men to secure an impressive 2-1 success at Premiership St Mirren after Calum Butcher was red carded on the hour mark.
Last weekend at Falkirk Robbie then lost both his starting central defenders through injury.
And when Inverness headed south for a Championship clash on Tuesday, United again finished a man short because Peter Pawlett saw red.
Robbie admits a win with 11 men on the park at the end – and no injuries – would be welcome.
“The last two games in particular have been tough,” he said.
“We had two centre-halves stretchered off, which limits your options to change things against Falkirk, and then you get a red card this week, which again limits your opportunities.
“We’ve managed to grind four points out of that so we’ve got to be pleased.
“I would like to take a game where we can just get through it without any issues.”
The ‘first leg’ success over Caley Thistle the other night saw American owner Mark Ogren fly over to take his seat in the directors’ box and he’ll be at Tannadice again tomorrow.
His trip has given manager and owner more time to sit down and thrash out plans for the future.
“We’ve had a few good meetings, it’s been great. He’s been pleased with the way things have been going. He’s been very supportive of everything, it’s been good.”
And if Robbie would like to give his boss a first Hampden visit to look forward to for next month’s semi-finals, promotion remains the No 1 priority.
“It would be good. It would be good for the fans and enjoyable for the owner but there is a long way to go here,” he added.
“Firstly we’ve got to get past Inverness but one appearance at Hampden, and even if we get further than that, isn’t going to make up for the four or five years of issues we’ve had here at United.
“We’ve still got to get promoted, that’s the main objective here, to get out of this league and start building.
“It’s about building momentum here and it’s about trying to take the club wee steps at a time.
“And we don’t want to get too far ahead of ourselves.
“Yes we’ve got a great opportunity to get through but we have to take care of this game first.”
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