* Newcastle lose 2-0 at second tier Brighton
* Macclesfield upset Cardiff, Luton beat Wolves (Adds detail)
By Martyn Herman
LONDON, Jan 5 (Reuters) - Chelsea striker Demba Ba made an instant impact with two goals on his debut as the FA Cup holders romped to an emphatic 5-1 victory at Southampton in the third round on Saturday.
The Senegal international, signed from Newcastle United on Friday, scored the London side's equaliser and their fourth before Frank Lampard's late penalty took the midfielder to joint second on Chelsea's all-time scoring list with 193 goals.
While Ba began in style, the doom and gloom continued at his old club Newcastle who lost 2-0 at Championship (second tier) Brighton & Hove Albion - one of several upsets on the day when England's lower-ranked clubs take aim at the big boys.
Goals from Andrea Orlandi and Will Hoskins earned Brighton, runners-up to Manchester United 30 years ago, a repeat of their fourth round victory over Premier League Newcastle last season, condemning Alan Pardew's side to an 11th defeat in 14 matches.
Cardiff City, runaway leaders atop the Championship, were the biggest victims, losing 2-1 at minor league Macclesfield Town while former FA Cup runners-up Luton Town, now outside the Football League, beat visiting Wolverhampton Wanderers 1-0.
Several clubs struggling in the Premier League flirted with defeats against lower league opposition before earning replays.
Fulham were held 1-1 at home by second division Blackpool, Wigan Athletic needed a late equaliser in a 1-1 draw with third tier Bournemouth and Sunderland recovered for a 2-2 scoreline at Bolton Wanderers who lost their top flight status last season.
Premier League Reading had to come from a goal down after one minute to beat third tier Crawley Town 3-1 away.
South coast seventh-tier minnows Hastings United, the lowliest survivors of the 758 clubs who began the 132nd edition of the world's oldest knockout Cup competition in August, had their fairytale cut short in a 4-1 defeat at Middlesbrough.
Chelsea's Ba needed only 35 minutes to start justifying the seven million pounds fee British media reported that Chelsea paid for his services when he crashed the ball into the net from a position virtually on the goal-line after Juan Mata's chip.
Jay Rodriquez had given Southampton an early lead but once Ba levelled they were no match for Rafa Benitez's side. Victor Moses made it 2-1 just before halftime and Branislav Ivanovic put Chelsea in control with Ba and Lampard adding some gloss.
Chelsea, bidding for a fifth FA Cup triumph in seven seasons, continued their unbeaten sequence in the FA Cup third round which now stretches back to 1999, while their last defeat in the competition, other than in a penalty shootout against Everton in 2011, was five years ago against Barnsley.
Manchester City's Mario Balotelli was a late substitute in their 3-0 home win over Gianfranco Zola's Watford, a day after the controversial Italian striker was splashed across British newspapers grappling with manager Roberto Mancini.
Goals from Carlos Tevez, Gareth Barry and Marcos Lopez eased the English champions into the fourth round.
Tottenham Hotspur's fine form continued with Clint Dempsey scoring twice in a comfortable 3-0 home win over third tier Coventry City, the side they lost to in the 1987 FA Cup final.
While hardly in the same league as some of the great FA Cup exits down the years, Macclesfield took the prize for the day's biggest upset, bridging a gap of 82 rungs on the English football ladder to stun Cardiff.
Cardiff, who lead the Championship by seven points, were ahead with five minutes remaining before Matthew Barnes-Homer equalised and then held his nerve to clinch victory from the penalty spot.
Minor league Mansfield Town have a chance to cause another uspet when they host Liverpool on Sunday. (Reporting by Martyn Herman, edting by Mark Meadows and Ken Ferris)