Making no attempt to disguise both his anger and frustration he said: " We should never have been put in a situation where we had to play two matches inside 48 hours.

"Our boys played some very good rugby, especially with ball in hand, and you certainly couldn't question their commitment.

"But the reality is that we conceded four no-tackle tries and that has to be a concern.

"Their out-half Dan Parks ran the show and in the last two years he has emerged as a quality out-half."

Williams said he was disappointed to have lost at home, but happy with the commitment and effort displayed against a very youthful Glasgow side.

"This game should have been played on a spare weekend, rather than two days after we had a difficult game against Munster in midweek.

"In a highly competitive and demanding sport it was wrong that our players were asked to put their bodies on the line for a second time in such a short space of time.

"Some of these players were just out on their feet at the finish."

Overall Ulster can have few complaints after losing a game they were expected to win.

They scored four tries so securing the bonus point, and perhaps it's just as well that Heineken Cup rugby next season was already assured after Connacht's defeat on Friday night.

Far too often Ulster were authors of their own destruction, gifting their opponents at the very least two tries with some sloppy and undisciplined defence.

In such a tight match such errors will prove decisive as Ulster found to their cost.

It's ironic that on this occasion Ulster's defence should have been found wanting for last time out against Munster defence proved the foundation for a much-needed victory.

In the end Glasgow were full value for their victory, man of the match visiting number 10 Dan Parks superbly marshalling a three-quarter line that was always enterprising and inventive, whereas Ulster's three-quarter line lacked any real cutting edge.

Before Ulster had time to settle the visitors struck for an opening try from wing Lome Fa'Apau from halfway with Parks adding the conversion.

The same player added a penalty before Ulster replied with a try by scrum-half Isaac Boss, close to the line with Paddy Wallace adding the conversion.

Fifteen minutes before the break Ulster No 8 Roger Wilson's try gave the home side the lead for the first time, but it wasn't to last long, visiting No 8 Johnny Beattie, breaking through Paddy Wallace's attempted tackle to leave the Scots 15-12 ahead at the break.

It was no more than they deserved and Ulster's problems were compounded within three minutes of the restart, visiting wing Max Evans scything through the heart of the Ulster defence with Parks inevitably adding the conversion.

Midway through the half a try by wing Simon Danielli offered Ulster fresh hope and things got even better for Ulster with a brilliant Tommy Bowe try.

Bowe raced clear from halfway after a kick ahead by scrum-half Boss with Wallace adding the conversion.

The home side now appeared well in sight of victory, but the Scots turned the game on its head. First Parks kicked the penalty before Thomas Evans raced clear for a try, Parks adding the conversion, and for good measure, the same player finally closed the door on Ulster with a penalty two minutes from time.

Ulster: Bartholomeusz, Bowe, Trimble, Dewey, Danielli, P. Wallace, Boss, J. Fitzpatrick, R. Best, Court, Harrison, del Fava, McCullough, N. Best, Wilson. Replacements: Brady, Young, Caldwell, Dawson, Campbell, O'Connor, McCrea.

Glasgow: Stortoni, Faatau, M. Evans, Morrison, T. Evans, Parks, Gregor, Va'a, Hall, Low, Palepoi, Turner, Brown, Barclay, Beattie. Replacements: Milligan, Newman, Tckachuk, Eddie, Pinder, Barrow, O'Hare.

Referee: Tim Hayes (WRFU).