The Cottagers drew 2-2 at United.
Sidwell told Sky Sports afterwards: "It's massive. I'm speechless, really. We put a lot of effort in, every one of us, defended well, a lot, but have come away with a point. Brilliant.
"It was hard. Everyone on the pitch put a great shift in. It's never easy coming here, we rode our luck a lot but came away with a point and hopefully we can kick on now for the rest of the season.
"It's not the best way to come and play at Old Trafford, you know you are going to be soaking up pressure for 90 minutes. We had chances to maybe put the game to bed in the first half, didn't take them, but we deserved a point."