Rangers 0 Dundee United 2: Rangers manager Ally McCoist believes an ongoing tax dispute rather than results on the park is more likely to plunge the club into crisis after they crashed out of the William Hill Scottish Cup to Dundee United.

The Scottish champions' only hope of silverware this season now depends on resurrecting their Clydesdale Bank Premier League title bid after falling a point behind leaders Celtic, who have a game in hand.

But as far as McCoist is concerned, the wait for a verdict in a tax tribunal with Her Majesty's Revenue and Customs (HMRC) that could land the club with a bill of £49m remains the biggest problem.

Asked if the club is now in crisis, McCoist said: “I think the crisis point comes with the tax case more than anything.

“That's the biggest problem that the club faces. I don't think there is any doubt about that.

“What we all need is clarification on what's happening so that we can move forward. The uncertainty regarding this tax issue is the biggest problem that we have. You could use the word ‘crisis’ in terms of the tax case, but we need to know one way or another where it stands and what we face so we can deal with it and move forward.”

McCoist was unable to replace top goalscorer Nikica Jelavic ahead of the transfer deadline, but could yet bolster his squad with free agents and expects to have the backing of owner Craig Whyte.

He said: “I think if I went to Craig with a player that we could maybe bring in he would certainly have a look at it. We've got two or three targets.

“I haven't gone as far as the finances but I know two or three players that would be appealing to us.”

Rangers' need for new players was highlighted when they ended yesterday's fifth round tie with a front pairing of Salim Kerkar — who has never started a game — and Northern Ireland international Andrew Little, whose injury problems meant he had not featured for the club since October 2010.

McCoist added: “We have injury problems in that department. Kyle Lafferty and Steven Naismith can both play there. We're going with two not really recognised strikers for the last 15 or 20 minutes but that's where we are.

“I don't have any complaints about how the two lads went about it, I just felt we lacked a bit of quality to open up United today and that was a disappointing thing.”

Meanwhile, McCoist denied reports that Rangers were ready to sell Kyle Lafferty — who is sidelined with a torn hamstring — to an English club for £1.75m.

He said: “To my knowledge that's absolute nonsense. We have been trying to re-sign Lafferty and offer him a new deal.

“That's my views on it and that's crystal clear. I know nothing about trying to sell Lafferty and I certainly don't know of any bids that came in. I told the player that this morning as well.”

Asked if a deal could have been struck without his knowledge, McCoist replied: “I wouldn't have thought so, no.”

First-half goals from Gavin Gunning and Johnny Russell secured a comfortable victory for United.