LONDON - Demba Ba's debut double helped Chelsea make a perfect start to its FA Cup defense with a 5-1 rout of Southampton in the third round, while Robin van Persie scored an injury-time equalizer to salvage a 2-2 draw for Manchester United at West Ham and earn a replay.

A day after completing his move from Newcastle, Ba took just 35 minutes to score at Southampton to cancel out Jay Rodriguez's goal.

After further Chelsea goals from Victor Moses and Branislav Ivanovic, Ba netted his second before Frank Lampard wrapped up the rout from the penalty spot.

Newcastle struggled without Ba, and was the only Premier League side to be ousted by lower-league opposition as Alan Pardew's side lost 2-0 at second-tier club Brighton.

At West Ham, Joe Cole had a successful return as he set up two nearly identical goals for the Hammers' James Collins. But Van Persie came on as a substitute to rescue United with a clinical finish in stoppage time.

Manchester City had no trouble ousting Championship club Watford, with a 3-0 victory, while Tottenham beat third-tier club Coventry by the same score in a rematch of the 1987 final.

The biggest upsets were provided by fifth-tier nonleague sides overcoming second-tier opposition as Macclesfield beat Championship leader Cardiff 2-1, and Luton defeated Wolverhampton Wanderers 1-0.

At Southampton, the 27-year-old Ba showed just how valuable he can be for Chelsea's quest for silverware this season as Fernando Torres was rested on the bench.

Ba's 14th goal of the season came after Juan Mata initially attempted to score from an acute angle, canceling out Rodriguez's opener. Chelsea went in front on the stroke of halftime after Moses collected a cutback from Ashley Cole and struck into the net.

Seven minutes into the second half, Ivanovic headed in Mata's cross, and Ba found the target again in the 61st after being set up by Eden Hazard.

The late penalty from Lampard allowed the 34-year-old midfielder to move to joint second on Chelsea's all-time leading scorers list.

As Southampton went out of the cup, it was a successful day for another south-coast side as Brighton eliminated Newcastle for the second successive season.

Andrea Orlandi put Brighton ahead in the 33rd minute, hooking the ball into the net with the outside of his boot after meeting Wayne Bridge's cross.

Injury-depleted Newcastle's prospects took a further turn for the worse when captain Shola Ameobi received a second booking for his late tackle on David Lopez in the 63rd minute. Brighton extended its lead late on when Will Hoskins slotted the ball through goalkeeper Rob Elliot's legs.

Three Premier League clubs face replays after being held by lower-league opposition. Wigan drew 1-1 with Bournemouth, Fulham was held by the same score by Blackpool, and Sunderland drew 2-2 with Bolton.

The lowest ranked team left in the cup saw its campaign end as seventh-tier side Hastings went down 4-1 at Middlesbrough.