Hammers boss Sam Allardyce was able to celebrate his 100th match in charge of West Ham with a victory - but it was nothing like as comfortable as it should have been.
But they wasted a host of chances to kill City off, and the team who inflicted a home defeat in Allardyce's first game at the helm two years ago threatened to repeat the trick as they drew level through Craig Noone and Peter Odemwingie.
That was until Ricardo Vaz Te popped up with a late winner to secure a 3-2 win and ensure Allardyce could toast his century in style.
"We had a mountain to climb with the way we started," said Mackay.
"I thought we were a shadow of ourselves in that first period but we scored a beautiful goal on the stroke of half-time to bring ourselves back into it
"We had a conversation at half-time and certainly put West Ham on the back foot in the second half.
"To quieten the crowd to that extent at 2-2, I'm very proud of the players."