SOUTHAMPTON, United Kingdom (AFP) - Demba Ba scored twice on his debut as holders Chelsea eased into the fourth round of the FA Cup with a 5-1 win over Southampton at St Mary's on Saturday.
Ba, signed 24 hours earlier from Newcastle United, cancelled out Jay Rodriquez's opener and scored the visitors' fourth after goals from Victor Moses and Branislav Ivanovic had put the Blues in control.
Frank Lampard came off the bench to win and score a late penalty that sealed a comfortable victory.
Ba's double suggested the Senegalese international could be an ideal deputy for the out-of-form Fernando Torres and showed he had an instant understanding with the rest of Chelsea's devastating front-line.
Interim manager Rafael Benitez showed he was taking the Blues' defence of their trophy seriously by naming a strong squad that had Juan Mata, Eden Hazard and Moses supporting Ba in the starting XI, with Torres on the bench.
But it was the Saints, who rested striker Rickie Lambert, who made the better start, pressing Chelsea all over the pitch and forcing them into mistakes.
Ba was struggling to get into the game and did not touch the ball until the sixth minute, when he beat Jose Fonte in the air.
David Luiz floated a shot straight at Saints goalkeeper Artur Boruc and Moses overhit a pass for Ba before the hosts took a deserved lead.
Jason Puncheon picked up a loose ball in the Chelsea half and swivelled on the spot to play a superb pass that put Rodriguez through on goal, and he slotted under Ross Turnbull.
It was a reward for the way the Saints had started, but it forced the holders into action.
Hazard curled just wide before they levelled when Ba finished off a superb move.
Moses's flick sent Hazard away down the left and he found Mata, who skipped past Maya Yoshida in the box and chipped over Boruc, with Ba applying the final touch on the line under pressure from Steven Davis.
Boruc twice almost gifted Chelsea the lead. First he was grateful to see his fumble from Moses's shot go past the post and then he was lucky to grab Cesar Azpilicueta's shot at the second attempt.
Guly Do Prado shot straight at Turnbull from distance but it was all Chelsea and they completed their first-half turnaround in added time.
Moses back-heeled the ball to Ashley Cole and then ran into the box to collect the return pass and fire left-footed into the bottom-right corner.
The Blues had found their rhythm and made the game safe seven minutes after the restart.
Mata was given the freedom of St Mary's on the left wing to pick out Ivanovic with a cross that the defender headed home unchallenged.
Luke Shaw stopped Hazard adding a fourth soon after but the Blues did not have to wait much longer for it as they started to run rampant.
Ramires found Hazard on the right and he nonchalantly passed into Ba to finish ahead of Fonte, who went off injured after the challenge.
There was still time for Turnbull to produce a superb double save to keep out Shaw at close range and then repel Davis's follow-up, before Boruc prevented Ba from scoring a debut hat-trick by saving his back-post header.
Lampard, out of contract at the end of the season, came off the bench to chants of 'Sign him up!' from the Chelsea fans and he converted the Blues' fifth from the spot after his flick hit a Southampton hand in the penalty box.