Arsenal goalkeeper Lukasz Fabianski had a birthday to forget as his error gifted Chelsea a 2-1 victory in Saturday afternoon's FA Cup semi-final at Wembley.
Theo Walcott put the Gunners ahead after 18 minutes when his volley took a deflection off Ashley Cole and beat Petr Cech.
Chelsea fought back and levelled through Florent Malouda, and sealed a return to Wembley when Didier Drogba latched on to a long ball ahead of the on-rushing Fabianski, and slotted into a empty net in the 84th minute.
Although substitute Andrey Arshavin went close in stoppage time, there was no way back for Arsenal, allowing Chelsea to claim capital dominance, while also quietly keeping themselves on track for the treble.
Walcott's goal was just reward for a sparkling start. The young England star was the pick of an Arsenal side whose movement was a joy to watch, even if their end product was not always the best.
Kieran Gibbs' cross was decent, allowing Walcott to let fly with a first-time volley that flicked off Cole's hand. The deflection did alter the direction of the ball, yet the feeling persisted that the Cech of three years ago would have kept it out.
Chelsea's equaliser arrived when Malouda cut inside Emmanuel Eboue and beat Fabianski at his near post, although it was hard to quibble with the Frenchman's accuracy.
Nicolas Anelka hit a post after robbing Abou Diaby inside the Arsenal box just before half-time and Chelsea continued to look the more likely scorers after the break, even though their opponents were, in patches, the better team.
Six minutes from the end, Fabianski inexplicably raced out of his area as Drogba brushed off Mikael Silvestre to reach Frank Lampard's long ball.
What should have been a 50-50 duel turned into a walkover as Drogba skipped round the Polish international and tapped Chelsea into the final, where they will meet either Manchester United or Everton on May 30.
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