Wellington: South Africa are on the verge of victory over New Zealand at tea on the final day of the third Test in Wellington after speedster Morne Morkel skittled through the top-order.

New Zealand, set the near-impossible target of 389 to avoid a series defeat, were 103-5 with Morkel taking all the wickets for the remarkable figures of 5-11 off 11 overs.

With New Zealand captain Ross Taylor suffering a broken forearm and taking no further part in the Test at the Reserve Basin ground, the hosts have only four tailend batsmen left. They are 1-0 down in the three-Test series and facing another defeat full in the face.

Morkel was on a hat-trick after cleaning up Dean Brownlie and Daniel Vettori with successive yorkers with the last two balls of his 10th over but Kane Williamson placed the first ball of his next over through mid-on for three.

The 21-year-old Williamson has been the sole rock of the New Zealand innings, surviving a painful strike in the groin and at least four edges behind the stumps to be 58 not out at tea with Kruger van Wyk on seven.

Morkel started his destructive campaign in New Zealand's second over when Daniel Flynn gloved a rising delivery through to wicketkeeper Mark Boucher to be gone without scoring.

Brendon McCullum also failed to get off the mark before Morkel trapped him lbw and New Zealand were two down for one run in the fifth over.

Opener Martin Guptill produced a gritty display, lasting nearly 100 minutes in the middle and facing 55 balls before he edged Morkel to Jacques Rudolph at gully and was gone for 18.

With the fiery Dale Steyn, Marchant de Lange and Vernon Philander supporting Morkel New Zealand were struggling for survival.

Brownlie faced 18 balls without scoring before launching into de Lange and taking 14 off one over, including three boundaries, but he was to add only one more run before Morkel struck again.

South Africa had resumed the day at 75 without loss and cracked on a further 114 at more than seven an over before declaring at 189-3.

AB de Villiers had a rollicking time with the bat racing to 68 off 49 deliveries, including eight fours and a six, before he was caught at long on by Williamson off Doug Bracewell.

The declaration came with de Villiers' dismissal leaving JP Duminy unbeaten on 33 off 23 balls including three sixes and two fours.

Meanwhile, Taylor, who suffered a broken forearm when hit by Morkel on the fourth day, was to undergo surgery on Tuesday and the New Zealand management said he would be sidelined for at least four weeks.