Few predicted the Championship side would put up much of a fight on Wembley's wide pitch that seemed perfectly-suited to Arsenal's mesmeric passing game.
Even fewer thought the Premier League team would need a huge favour from the Reading keeper to progress with a 2-1 win that maintained the hopes of retaining their FA Cup crown.
The match, which began as a drab spectacle and ended in a rip-roaring end-to-end contest, deserved better than to be decided by Adam Federici's devastating error when he let Alexis Sanchez's tame shot squirm under his body in extra time.
The Australian left the pitch in tears as Arsenal celebrated reaching a record 19th FA Cup final where Liverpool or Aston Villa await.
“In the end we were a bit lucky because their goalkeeper made a mistake. I understand he is distraught but he kept them in the game for long periods,” Wenger told reporters.
“Reading really wanted it, they were ready to die on the pitch to get to this final. We have to congratulate them for the effort they put in today.”
Reading were tenacious and, while they frequently lacked quality in advanced areas, they forced the Premier League aristocrats to slum it in the sort of match more commonly seen in the lower leagues.
Much of the game was ugly with Reading keeping their well-marshalled lines behind the ball with express instructions to snap at the heels of their opponents and prevent them picking a path through the centre of the Wembley surface.
But when Gareth McCleary equalised nine minutes into the second half after Sanchez had given Arsenal the lead with the first of his two goals, there was, for a brief moment, the sense a shock could be on the cards.
Arsenal regained the upper hand, however, and Sanchez's winner in stoppage time in the first period of extra time ensured they did slightly better than in last season's semi-final when Championship opponents Wigan Athletic took them to penalties.
“Comparable to what we faced last year we have made a big improvement,” Wenger quipped.
Original source: Wenger's joy after Arsenal reach final