Arsenal boss Arsene Wenger admits he was caught by surprise by Reading's physicality in his side's 2-1 win at Wembley.
The Gunners had to work extremely hard to battle past Steve Clarke's men as they reached their second consecutive FA Cup final.
And the Frenchman says Arsenal were lucky to avoid penalties after goalkeeper Adam Federici's mistake gifted his side the winning goal.
"It was a difficult game against a very resilient, well-organised, physically very strong side," Wenger said.
"They were a committed Reading team who were comparable to what we faced last year against Wigan Athletic. We have improved a bit because we needed the penalties last year but it meant we got through.
"We had a lot of possession - I think we had 23 shots on goal and 72 per cent possession - but it was still difficult to find space because they defended very well.
"I was surprised how strong they were in the challenges. In the second half they became even stronger in the challenges and we suffered a little bit then, and lost some balls that we're not used to losing.
"In the end we were a bit lucky because their goalkeeper made the mistake and I can understand that. He kept them in the game as well for long periods.
"There are so many top-level players in the Premier League that many good players go down to the Championship. If you look at the number of players who play in the Championship, many of them have played in the Premier League."