Watch Oldham Athletic vs Leyton Orient Live Streaming
Watch Oldham Athletic vs Leyton Orient Live StreamingO'Neill said: "It's great to be back at Wembley again - even on that pitch.
"I didn't enjoy the occasion at all last week so there is a chance to put that right now.
"It took us time today before we treated it like a quarter-final in the FA Cup.
"You need character and determination to fight and we didn't have that in the first half.
"But it came back in great abundance.
"It's fantastic for the football club to be in the semi-finals and I genuinely feel for the supporters. They were fantastic.
"Even at 2-0 down to a Championship club they were cheering us on and that was a big boost."
Villa were staring at an upset when Shane Long's two goals put the Royals in control at the break but from the moment Ashley Young pulled one back within two minutes of the restart the Premier League side moved through the gears.
