Southampton captain Kevin Phillips scored one goal and created two more as Southampton cruised past Northampton and into the FA Cup fourth round.
Phillips broke the deadlock in the 29th minute at Sixfields, crashing in an unstoppable left-footed half-volley.
The Cobblers were back on terms within 60 seconds thanks to a Lee Williamson equaliser but Southampton were soon 2-1 up after Phillips set up Peter Crouch.
And the Saints skipper went on to set up Jamie Redknapp in the second half.
David Prutton set the attack in motion before Phillips carried the ball to the byline, where he cut back to Redknapp whose right-footed effort beat Town keeper Lee Harper. Man of the match - Antti Niemi
The hosts, who saw a clutch of chances denied early on, at least made the Premiership side sweat when Williamson advanced unchecked from midfield to pass Antti Niemi with a powerful shot.
Southampton's riposte was not long in coming though with Neil McCann supplying Phillips who, with his back to goal, teed up the on-rushing Rory Delap.
Northampton boss Colin Calderwood:
"They had quality all over the park and in the end that was the difference between the two teams.
"But if we can learn to play with their precision and power and passion then there's no doubt we'll became a better side ourselves.
"I'm not going to get too down and depressed about it though because we got a lot of media coverage from the tie and also we got a good crowd down here."
Southampton manager Harry Redknapp:
"It was a win and that's the main thing.
"There are no easy games in the third round of the FA Cup - you only have totake a look at the results from all over the rest of the country to see that.
"There can be upsets anywhere in the Cup and I should know because I've been involved in a good few of them in my time, both on the right end and on the wrong end of results."