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Former Brentford goalkeeper Paul Smith could not prevent his old club progressing to an FA Cup date with Chelsea despite saving a penalty for Southend.
Brentford 2 Southend United 1
Clayton Donaldson gave Brentford a lucrative London derby against Chelsea in the FA Cup fourth round with his winner against plucky Southend United at Griffin Park.
Paul Hayes had opened the scoring for Brentford but League Two Southend rallied and claimed an equalizer through Barry Corr.
Former Brentford goalkeeper Paul Smith was inspired form against his old club and saved a penalty from Harry Forrester among a series of great saves.
But former Hibernian and York striker Donaldson needed a deflection to beat Smith for the 76th-minute winner.
Birmingham City 1 Leeds United 2
El-Hadji Diouf rolled back the years on his 32nd birthday to guide Leeds United toward a fourth-round date with Tottenham at Elland Road
Wade Elliott had given Birmingham City a first-half lead when he connected with Nathan Redmond's cross.
But Diouf then set up Ross McCormack to equalize in the 70th minute before hitting the winner himself from the penalty spot six minutes later after Paul Robinson handled inside the area.
Leyton Orient 1 Hull City 2 (after extra-time)
Hull City needed extra-time to see off the challenge of Leyton Orient at the Matchroom Stadium in East London.
Hull had taken the lead in the 41st minute when Nick Proschwitz headed home Liam Rosenior's cross from the right.
The visitors hung on until three minutes from the end of normal time when Dean Cox found the net from Moses Odubajo's flighted ball.
However, with five minutes left in extra-time, Tom Cairney hit the winner for Steve Bruce's side, who will now play host to fellow Championship side Barnsley in the fourth round.
MK Dons 2 Sheffield Wednesday 0
MK Dons reached the FA Cup fourth round for the first time in their short history with a 2-0 win over Championship strugglers Sheffield Wednesday at stadium:mk.
Shaun Williams opened the scoring for the Dons from the penalty spot in the 28th minute after Lewis Buxton pulled back Dean Bowditch in the area.
Bowditch sealed a fourth-round tie at Queens Park Rangers when his 75th-minute free-kick somehow bounced past Wednesday goalkeeper Stephen Bywater.