A successful side needs a strong spine - and it seems boss Harry Redknapp may have hit upon just that.

During their FA Cup final season, Saints' success was primarily built on a stiff core through the middle of the pitch - Antti Niemi, Michael Svensson, Matt Oakley and James Beattie.

Since then long-term injuries to Svensson and Oakley and a blighted time for Beattie has seen that spine torn apart and nobody has stepped up to fill the gaps on a permanent basis.

Now they have and Saints look all the better for it.

Niemi, Calum Davenport, Jamie Redknapp and Kevin Phillips look exactly the strong spine Saints need.

They can't do it alone and need quality around them but, once you have those basics right, you can build from there.

The quality of all four was evident on Saturday when their displays helped Saints avoid a potential FA Cup upset at Northampton.

Niemi, though he might have kept out the Cobblers' goal, was superb all afternoon.

Davenport looks like a player still learning but with the confidence and personal strength of a man prepared to take responsibility and be a star of the future.

Jamie Redknapp isn't just exceptional on the ball, he also has the desire and heart for the fight.

And the icing on the cake is Phillips, who is looking back to his brilliant best.

It might be coincidence but, since the departure of Beattie became inevitable, Phillips has seemed reinvigorated.

His performances leading the team as captain have been superb, not only in terms of goals but in his all round contribution.

He is clearly relishing being the undisputed main man in attack. It's a role he was born to play and he does it well.

Phillips opened the scoring at Sixfields with a peach of a volley on 29 minutes of an open first period which saw Niemi have to make a couple of stops, Phillips having missed a chance after 15 seconds, and Saints having had two decent penalty appeals turned down.

That lead lasted less than a minute, however.

As is so often the case this season, Saints backed off, this time as Lee Williamson ran towards goal, and the Northampton midfielder unleashed a fierce 25-yarder that Niemi got a hand to but couldn't keep out.

The game swung into life as a full-blooded cup tie as Northampton sensed the chance of an upset.

Niemi pulled off a good save from Josh Low before Peter Crouch gave Saints the lead again.

Phillips provided the defence-splitting pass and Crouch ran onto it to finish calmly, low under the advancing keeper.

Niemi again came to the rescue to scramble a Scott McGleish header off the line and ensure Saints had a half-time lead.

All the talk at the Sixfields was of potential upsets, even with Saints leading at the break.

But Southampton killed off the game five minutes after the re-start.

Phillips raced onto a David Prutton ball over the top and did well to stay on his feet as he was twice fouled by a chasing Northampton defender.

He got to the by-line, glanced up and pulled the ball back to Jamie Redknapp who looked composed as he fired home his first goal for the club.

It really took the wind out of the Northampton sails and, for a large period, Saints looked the more likely to score again, with Tommy Jaszczun having to clear off the line and Lee Harper saving well from a Phillips free- kick.

But, as the game drew to a close, the Cobblers went all out and Niemi came into his own again.

First he produced a good save from Eric Sabin's header and then one of the stops of the season when Trevor Benjamin seemed certain to score.

Somehow Niemi reacted to the shot from just yards away, flung himself to his right and managed to stop it and push the ball clear of danger.

Perhaps it was worrying that Saints were pushed so hard by a League Two side but, just against Fulham in the 3-3 Premiership draw, there were again more reasons for optimism.

Perhaps the players around the spine still aren't quite in perfect balance, but at least the spine is there.

And, even better, it's strong - and not palpably brittle as has been the case too often in the past 12 months.