The Dutch keeper had to pick the ball out of the net just nine minutes after Kun came on for Nigel de Jong and three minutes later he watched the new signing from Atletico Madrid hook the ball over his head to set up David Silva.
To wrap up the game, he was beaten by a Sergio thunderbolt from 25 yards just 23 minutes later.
You might say he was impressed by what he’d seen!
“It was quite funny because it was my first game in the Premier League and Swansea’s first game back in the top flight,” said Vorm.
“I had just flown in to join the club a few days earlier and we played City on a Monday night and in truth, it was a bit of a blur because so much happened.
“I knew City had bought some very good players in the summer but Aguero was the one that stood out for me.
“I knew him from seeing Atletico Madrid play on TV and knew he was a talent.
“So, here is little Swansea playing Man City at the Etihad in a live TV match on Monday so it was a little like being thrown in at the deep end.
“I didn’t know if Sergio would start or not but when we did begin, obviously he was on the bench but although we reached half-time 0-0, I had already made so many saves and we were clinging on a bit.
“But because City hadn’t scored, we were thinking that maybe we had a chance of causing an opening day surprise.”
The Swans’ resistance lasted another 12 minutes after the break before Edin Dzeko finally opened the scoring to make it 1-0.
Then Sergio was brought on to replace De Jong and Vorm got his first look at the 23 year-old up close.
“You could see straight away that he was special,” said Vorm, now goalkeeper coach at Tottenham.
“I think he’d been on less than 10 minutes when Micah Richards crossed from the right and Aguero scored a tap-in at the far post.
“A few minutes after that he chased a ball to the goal-line and hooked it back over for Silva to score – I thought it was definitely going out so I’m not sure how he got to that.
“And of course, his second and City’s fourth was from a distance and was unbelievable.
“That this small guy could generate so much power in his legs and for me it was like, ‘OK, he has poached a goal, made another and can hit them from anywhere’ – not a bad first 30 minutes or so in the Premier League!
“We all knew he had quality, but to start like that and show different elements from his locker was pretty impressive.
“And now, 10 years later, he has shown that he’s one of the best strikers to ever play in the Premier League.
“I’ve never forgotten that night, as difficult as it was, and it’s fair to say Sergio made a huge impression on me.
“I followed football and always have and as a football fan, the moment he scored the winner against QPR in 2012 is something I will never forget.
“He is undoubtedly one of the best strikers I ever played against, an inspiration to kids who want to play and I hope he gets to say his farewell on Sunday to the City fans and I wish him nothing but good luck in the future.
“And if he could be part of winning the Champions League, that would be the perfect end to his time at the Club.”