CELTIC striker Scott McDonald once missed out on a move to Dundee United ... because he went for a wee!

The Aussie hitman was taking part in a gruelling cross-country run to assess his fitness during a trial with the Tannadice club in 2004.

But when he turned in a slow time, then United boss Ian McCall vetoed any chance of a deal.

But McCall was unaware that McDonald had taken time out from the run for a Paula Radcliffe-style comfort break - and that was the reason he lagged behind.

McDonald was then snapped up by Motherwell - where he hit 42 goals - before earning a £700,000 switch to Celtic two years ago.

The "watergate" incident was revealed today by United star Garry Kenneth, who ran round the course alongside McDonald.

He recalled: "I was his running partner around Camperdown Park. There was one day when he actually had to nip into the woods while we were out doing the run.

"I don't know for certain if that's what cost him the chance of signing here, but it certainly caused a few laughs among the lads.

"He was a bit bigger back then and I remember that even I beat him in the race.

"Scott wasn't at his fittest, but since then he's proved to be a really good signing for Celtic.

"Looking back, if we had maybe taken a gamble on him like Motherwell did then it would have paid off. "

Kenneth was speaking ahead of Celtic's visit on Sunday and warned United are desperate to end a mini-form slump that has seen them slide to fifth place.

He said: Celtic games always seem to bring the best out in us. We've taken them to the wire in every match this season.

"It would mean so much to our supporters to get the three points and keep on the tail of Hearts for that third spot."