Steven Caulker's 62nd-minute header was the difference as the Bluebirds saluted in the first Premier League match between the two sides and it was a moment which had the manager in a very upbeat mood after a few tough weeks.
"It's a good day all round," Mackay told Sky Sports. "It was a hugely important day, in terms of locally to south Wales, but also as far as we were concerned in terms of the background noise of the last three or four weeks.
"That win certainly helps to put a lot of smiles on people's faces and you see the atmosphere, I've never known anything like it and to come away with, not only the win, but also the performance as we were playing a really good team here today.
"It's a team that have been winning well in Europe, are a mid-table Premier League team who have been in the division for three years. For us to come up this year and play to that standard, especially in the second half, I thought we were very dominant."
He added: "There's pressure on me every week, on the staff and the football club.
"It's a tough, uncompromising league, but it's the only place to be. We've got good people here, who are enjoying playing in this division."
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