Arsenal manager Arsene Wenger has refused to point the finger at goalkeeper Wojciech Szczesny for allowing Gareth McCleary to equalise and put the club's attempts to win a record 12th FA Cup on the brink of ruin.
Alexis Sanchez scored twice to ensure the Gunners reached the record 19th final, after Adam Federici allow the Chilean's extra-time shot to go through him as the Royals were cruelly denied.
Szczesny replaced number one David Ospina for the semi-final clash and his second half error almost scuppered Arsenal's hopes of ending another encouraging season with a piece of silverware, but Wenger was unwilling to lay all the blame at the Polish international.
"I have to watch [McCleary's goal] again," he said. "I thought at first it was not in but it took some time for the referee to never the goal and on slow motion maybe he goes back a little bit when the ball bounces
"It was certainly over the line. We have to analyse it. The cross before that shouldn't come in as well. It was a combination of mistakes."
While victory for Chelsea over Manchester United leaves Arsenal seemingly playing for second place in the Premier League, they face having to do it without captain Per Mertesacker who was replaced in the second half by Gabriel.
But Wenger has attempted to calm fears over the German centre-back's injury, who limped off gingerly at Wembley.
"Ankle," Wenger responded when asked about the nature of Mertesacker's problem. "He limps badly so it doesn't look too good."
Arsenal came into the game having won their last eight league games in succession but showed little of the quality which had accompanied that winning run as Reading pushing them all the way.
Wenger believed that despite Arsenal having 23 shots on goal during the 120 minutes his side lacked a cutting edge throughout the game, after being deprived space to play by the Championship side.
"What was missing was speed of combination and sharpness in the final third," the Frenchman added. "I believe in the spirit and concentration was there you have a bit of sharpness and create more clear cut chances.
"Fantastic contribution he looked to struggle to get into the game at the start but he has that stubborn resilience and that bit of potential that allowed him to."