Matt Oakley scored his first goals of the season to fire Southampton into the FA Cup fifth round with an extra-time replay win over Millwall in a cracking tie at the New Den.

The Saints midfielder signed an extended contract for Gordon Strachan's side last week, and put the visitors ahead with a 22nd-minute shot.

But his winner in extra-time finally finished off stubborn resistance from the First Division side, who had equalised through Steven Reid, to set up a home tie with Norwich.

Southampton defender Francis Benali presented Millwall with the first chance of the game, playing a sloppy pass straight to 19-year-old Charley Hearn in only the third minute.

Hearn was clean through on goal, but failed to capitalise on the gift, with Benali quick to track back and block his shot from inside the penalty area.

From the resulting corner Dennis Wise let fly with a wicked drive, but his shot was cleared. In his frustration Wise earned a booking for a reckless tackle.

Reid was called up by the Republic of Ireland this week and proved his quality with a rasping 30-yard free-kick in the 18th minute.

His right-foot rocket had Saints goalkeeper Antti Niemi beaten, but flew just inches over the crossbar.

But the visitors opened the scoring in stunning fashion after 21 minutes when Paul Telfer's right-wing cross deflected off Reid to Jo Tessem,

He chested the ball down for Oakley and he drilled an unstoppable shot past Tony Warner for his first goal of the season.

But the home side sprung a surprise with a 37th minute equaliser. Paul Ifill passed to Steve Claridge on the right wing and his low cross found the onrushing Reid.

Niemi parried his first effort but Reid netted the rebound.

Beattie has 16 Premiership goals to his name this season, but 21-year-old defender Paul Robinson was doing a good job of winning the physical battle against him, and was booked for an over-zealous challenge on the high-profile striker.

Millwall enjoyed a good spell of early second-half pressure, forcing a flurry of corners. Wise found Claridge, who turned to shoot and forced Niemi into a fingertip save.

Gordon Strachan had seen enough and threw on Kevin Davies, who scored the equaliser in a 1-1 draw between the sides at St Mary's.

In the 68th minute Beattie rose to head Telfer's cross against the upright, with keeper Warner rooted to the spot.

And the 24-year-old striker came close to winning it in the 83rd minute from Chris Marsden's left-wing cross, but Warner beat him to the ball.

Beattie was all alone shortly afterwards when he unleashed a shot which hit Robinson to deflect narrowly wide of the Millwall goal.

Tempers then flared between former Portsmouth player and manager Claridge and Saints captain Marsden, with the latter earning a booking as the tie went into extra-time.

Both sides looked nervous in a tense first period, with passes going astray.

But Beattie drew a save from Warner with a firm drive from the edge of the penalty area.

Reid was robbed in possession by Marsden, and Oakley had time to pick his spot from the edge of the area, beating Warner's despairing dive with a sweet right-foot shot.

Time was running out for Millwall, and worried manager Mark McGhee sent on Sergei Baltacha to play as an extra attacker.

But Southampton were content to keep possession and dominated play until a late burst from the home side, with Niemi smothering at the feet of substitute Ben May.

Teams:

Millwall: Warner, Lawrence (Baltacha 111), Ryan, Ward, Robinson, Ifill, Hearn (Kinet 86), Wise (May 104), Reid, Livermore, Claridge.

Subs Not Used: Gueret, Roberts.

Booked: Wise, Robinson, Claridge.

Goals: Reid 37.

Southampton: Niemi, Telfer, Benali, Lundekvam, Michael Svensson, Fernandes (Ormerod 105), Anders Svensson, Oakley, Marsden, Beattie, Tessem (Davies 65).

Subs Not Used: Jones, Williams, Arias.

Booked: Beattie, Marsden.

Goals: Oakley 21, 102.

Att: 10,197

Ref: M Halsey (Lancashire).