Thierry Henry headed home the opener a minute into the second half and Zlatan Ibrahimovic found the net with a delightful chip at the death to complete a second goalscoring cameo from the bench in a week which glossed over a rare abject performance from the Catalan club.
Pep Guardiola opted to leave the Swedish striking sensation on the bench alongside Andres Iniesta and newly-crowned European Footballer of the Year Lionel Messi following their heroics in SundayÃ¢â‚¬â„¢s Ã¢â‚¬ËœEl ClasicoÃ¢â‚¬â„¢ and the decision almost backfired.
Bojan Krkic and Pedro were handed starts alongside Henry in the Barca frontline but both failed to impress against a hard-working Xerez side in a half lacking in fluency and suffering from the frequent interruption of the offside flag.
BarcaÃ¢â‚¬â„¢s best chance fell to Yaya Toure after XaviÃ¢â‚¬â„¢s floated free-kick found its way to the wantaway midfielder through a crowded six-yard box, but the ball bounced at an awkward height for the Ivorian and he could only make a failed attempt to divert it past Xerez goalkeeper Renan with his chest.
Ukrainian centre-half Dmytro Chygrynskiy spurned an opportunity to head the away side into a lead at the far post following a Xavi corner to bring the action-starved half to a close.
GuardiolaÃ¢â‚¬â„¢s half-time message to his side must have been ringing in the playersÃ¢â‚¬â„¢ ears when they entered the field for the second half as Barca raced from the blocks to break the deadlock after just 58 seconds of play.
The ball was worked neatly between Saydou Keita and Maxwell on the left flank before the Brazilian full-back whipped in a ball for Henry to get across the defender and power a header past the the goalkeeper and into the roof of the net from close range.
Despite storming into the lead, Barca remained languid and their indifferent performance forced the introductions of Messi, Ibrahimovic and Iniesta as the half progressed.
The presence of Messi lifted his teammates and the majestic Argentine raised the tempo of the game by purposefully buzzing around the pitch but with the teams separated by just a single goal, Xerez grew in belief and put up a brave fight despite rarely threatening ValdesÃ¢â‚¬â„¢ goal.
The home side Ã¢â‚¬â€œ playing in the Spanish top-flight for the first time in their 62 year history Ã¢â‚¬â€œ applied a brief spell of pressure on the Barca backline as the game entered the final ten minutes but the unconvincing partnership of Rafael Marquez and Chygrynskiy managed to stand firm.
BarcaÃ¢â‚¬â„¢s most creative period of play came in the three minutes of stoppage time.
Iniesta charged down an attempted clearance and the ball fell kindly to Messi who drove into the 18-yard box before planting a shot that cruelly struck the foot of the RenanÃ¢â‚¬â„¢s left-hand post with the goalkeeper beaten.
Iniesta then squandered a glorious opportunity to double his sideÃ¢â‚¬â„¢s advantage after Ibrahimovic sent a measured pass across goal into the path of the onrushing Spaniard at the far post who just had to hit the target to score but fired a shot high into the side-netting.
However, Barca were not to be denied a second as Messi poked a ball through two defenders to send Ibrahimovic clear to chip the ball with deft elegance over the advancing Renan into the net from the edge of the area to extend his goal tally for the season into double figures.
Five points now separate Barca and Real at the La Liga summit with the Madrid outfit having played a game less.
Xerez: Renan, Francis, Aythami, Gioda, Casado, Keita, Bergantinos, Sanchez (Armenteros, 73), Calvo (Antonito, 57), Orellana, Bermejo
Barcelona: Valdes, Dani Alves, Marquez, Chygrynskiy, Maxwell, Toure, Xavi, Keita, Pedro (Messi, 55), Henry (Iniesta, 83), Bojan (Ibrahimovic, 66)
Man of the Match: Lionel Messi Ã¢â‚¬â€œ Lifted an otherwise abject Barca performance and was unlucky not to get on the scoresheet before sliding Ibrahimovic through to score at the death.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news