Ruud Van Nistelrooy's penalty in the first half was the difference between the sides and ended our unbeaten start to the season.
Clear-cut chances were few and far between with United keeping us at distance although Roy Carroll did well to save from Robbie Keane and Simon Davies.
At the other end, Robbo was at his best to deny Ronaldo and a point-blank header from David Bellion.
"It shows just how far this club has come in a short space of time that we're all disappointed about getting beaten by a team like Manchester United," reasoned Robbo.
"We went into the game expecting to get something out of it and were disappointed we haven't.
"We didn't play particularly well in the first half, certainly not as well as we have been. We didn't create much. I thought the second half was a much better performance and everyone was very down afterwards, very disappointed."
As for another fine display, the England number one added: "It's what I'm there for. It's difficult for me to influence a lot of the game although I do try as much as I can. It's important for me to do my job."
Paul Robinson says it shows how far the team has come that the lads were so disappointed not to get any reward from the clash against Manchester United.