And O'Donnell believes his side can now move forward without an added pressure on their shoulders.
He said: "There's a great bunch of lads here and we've got a good work-ethic but since we got the win there has been a bit more of a buzz around the squad.
"We never doubted we'd get a win and now we have one we'll go out with a bit more confidence and a bit more freedom."
The forward scored his first try for the club during last Friday's match as Warriors were able to play free-flowing attacking rugby on the artificial pitch.
And O'Donnell admits he was delighted to open his Worcester account. He continued: "It was a good feeling to get my first try for the club as we don't get many opportunities to score as props.
"I think I got the ball on the 22 but by next week I'll probably say I ran from the halfway line to exaggerate it even more!"
Warriors will be looking to recreate their performance when Leicester Tigers visit Sixways this Friday (7.45pm kick-off).
And O'Donnell insists his side will have to be at the top of their game to secure another win.
He added: "It's going to be a whole different ball game on Friday. Leicester have a very good team and a very good game plan.
"We expect it to be a difficult test. If we play the way we did against Cardiff and get a bit of dominance in the scrum and lineout, then hopefully we can get another win."
Seated tickets for the match start from £15 for adults and £7.50 for juniors and are available by visiting the Warriors Box Office, calling 01905 459309 or clicking here.