Kalou provides relief for Scolari's back trouble

It will not just be Southend's sea mists and its unnerving sense of isolation that will make Luiz Felipe Scolari shiver when in years to come he is reminded of his one day out on the Essex coast. Not many World Cup-winning coaches have come close to being humiliated at Roots Hall but at one goal down, Scolari might have wondered whether he was about to be an unlikely first.

The Chelsea players tossed their shirts triumphantly into the crowd at the end, strutting off the pitch as if he they had just slayed a major Champions League opponent, rather than won an FA Cup replay against League One strugglers. Chelsea proved themselves still to be a complete shambles when it comes to defending set-pieces but fortunately for them they were up against the Shrimpers last night rather than one of the bigger fish.

The drama began when Didier Drogba was left at home, thrown out by Scolari as punishment for his risible performance against Manchester United. It continued when the referee Chris Foy then called the game off more than an hour before kick-off because of the fog before changing his decision when it disappeared. The mist may have lifted but the confusion remained at the heart of Chelsea's defence.

In the end it was Michael Ballack, his first goal since he scored against Scolari's Portugal at Euro 2008, who hit the equaliser before half-time. Salomon Kalou calmed things further with a goal on the hour and then Nicolas Anelka and Frank Lampard made things safe. Chelsea now face Ipswich in the fourth round of the FA Cup, Southend turn their minds to Stockport County away. But they do so knowing that they have wreaked havoc from set-pieces against Chelsea just as efficiently as United did on Sunday. For Chelsea there is a serious issue around Joe Cole's fitness now, the midfielder was struggling to walk after twisting his knee.

With Scolari ducking the post-match press conference following his broadside against his players on Tuesday it fell to John Terry to explain what effect the last few days had on the team. "We have under-performed recently and the manager was right to criticise us for not fighting enough," Terry said. "This was an opportunity for us and we showed great spirit. It was not the best of starts but after 30 minutes we upped the tempo and fully deserved to win. It [conceding from set-pieces] is one of those things. You go through spells like it in a season."

It has been quite some spell from Chelsea, this was the fifth out of seven goals they have conceded in their last four games to come from a set-piece. Scolari's new zonal marking system lasted all of 15 minutes and just one Southend corner – and that was taken short – before it buckled. Adam Barrett got between the unimposing Alex Da Costa and Anelka to head in at the back post.

Had it not been for Petr Cech's point blank save from Alex Revell on 38 minutes, then who knows what might have befallen Chelsea, still one goal down at the time. It barely needs saying that Roman Abramovich was not in town last night but his boardroom lieutenant Eugene Tenenbaum was there in person to watch alongside chief executive Peter Kenyon. They could not have been sure the equaliser was coming.

In the build-up to Ballack's goal Johnny Herd cleared off the line from Joe Cole, and Southend ranged 11 men behind the ball. Barrett and Peter Clarke were excellent in the centre. Just before half-time Clarke, the scorer at Stamford Bridge collided with goalkeeper Steve Mildenhall and, when the ball broke free, Ballack volleyed home.

The goal may have steadied Chelsea's nerves but it did nothing for their poise at corners. They came close to conceding yet again when Jean-Francois Christophe was first to a Junior Stanislas corner and headed over the bar before the hour. Eventually the breakthrough came when Joe Cole hit a cross-field ball that Kalou ran on to down the right wing and beat Mildenhall at his far post.

Scolari substituted the unimpressive John Obi Mikel at half-time and brought on Juliano Belletti. Anelka scored the third after Lampard and Kalou combined to play him in. Kalou returned the favour to Lampard, cutting the ball back to him for the fourth goal after Franco Di Santo had done well to win possession in midfield. Chelsea face Stoke City on Saturday, and they know a thing or two about scoring from set-pieces.

Southend United (4-5-1): Mildenhall; Sankofa, Clarke, Barrett, Herd; Revell (Betsy, 85), Grant (Francis, 80), Moussa, Christophe, Stanislas; Barnard (Freedman, 73). Substitutes not used: Walker, Joyce (gk), O'Keefe.

Chelsea (4-1-4-1): Cech; Bosingwa, Alex, Terry, A Cole; Mikel (Belletti, h-t); J Cole (Di Santo, 76), Ballack, Lampard, Kalou; Anelka. Substitutes not used: Cudicini (gk), Ivanovic, Carvalho, Mancienne, Stoch.

Referee: C Foy (Merseyside).

FA Cup fourth round

Revised draw:

Cardiff City v Arsenal

Chelsea v Ipswich Town

Cheltenham Town or Doncaster Rovers v Aston Villa

Derby County v Nottingham Forest

Hartlepool United v West Ham United

Hull City v Millwall

Kettering Town v Fulham

Liverpool v Everton

Manchester United v Tottenham Hotspur

Portsmouth v Swansea City

Sheffield United v Charlton Athletic

Sunderland v Blackburn Rovers

Torquay United v Coventry City

Watford v Crystal Palace

West Bromwich Albion v Burnley

Wolverhampton Wanderers v Middlesbrough

Ties to be played over weekend of 23-25 January