Leeds boss Neil Warnock said the decision to award Manchester City a soft penalty did his side no favours in their FA Cup defeat at the Etihad.
Warnock admitted his side were second best but felt aggrieved by the award of the spot-kick, given by referee Mark Clattenburg for the slightest tug on Aguero by United defender Tom Lees.
"I know Mark sees it differently and he's had a good game today but he wouldn't give a foul anywhere else on the pitch," said Warnock.
"The lad is clever the way he appeals but it's such a soft penalty.
""And so we're 2-0 down after 14 minutes. You think the worst but I think they've done really well.
"We have had great cup runs this season but I think in the first 10 minutes the young lads were a little bit overawed. But we hung in there and I was quite pleased they didn't fold.
"The second goal is vital when they're desperate to get a result but it's never a penalty in a million years.
"Let's be fair, they were still better than us but it made it easier for them."