The third-round clash, which has already been postponed twice due to the bad weather, looks to have little chance of going ahead on Saturday with the Paties Road pitch now frozen.
Due to a two-week break over Christmas and New Year, that means it is likely to be January 8 before the match has a chance of finally being played.
But even that will be too early for Robertson after he joined the long list of people who've come a cropper in the snow and ice.
"He slipped on the ice and broke his foot, meaning he's likely to be out for seven or eight weeks," said United manager Stephen Osbourne.
"That's a major blow as he's been an ever-present for us this season and has been doing well."
Osbourne is worried the delay in getting the game played is hurting their chances of pulling off an upset against the West Region giants.
He added: "Before the game was called off the first time a fortnight ago, there was a buzz about the place and I was really pleased with how the boys were not only playing but also applying themselves on the park.
"But when you don't have any games it tends to go a bit flat and it is very frustrating for everyone that the weather is stopping us from getting the match played."