Cape Town - The Stormers returned to the top of the Super 15 with a 19-13 win over Waratahs at Newlands on Saturday.

But for the second week in a row, the Cape Town side were outplayed in the second half and had to hang on to win and claim top spot ahead of Waikato Chiefs of New Zealand because they have won one match more.

Stormers led 16-3 at half-time, but their Australian opponents dominated a scrappy second half in wet, slippery conditions.

It was the 10th win in 11 matches for the Stormers, but they have yet to earn a bonus point for scoring four tries in a match.

They looked capable of breaking the bonus-point drought when they scored two tries within 16 minutes in the first half and hammered at the Waratahs line seeking a third before the break.

But they seldom looked like adding to the try count in the second half.

"We're the first to admit we haven't played our best rugby but I thought we improved this week," said Stormers centre and captain Jean de Villiers.

He added that the side's next two matches -- away to South African rivals Sharks and Bulls -- will give a strong indication of their prospects for the rest of the season.

Waratahs loose forward and captain Rocky Elsom said he was disappointed with his team's first-half performance.

"Our strategy was spot on, but our execution let us down," he said.

Fly-half Berrick Barnes kept Stormers under pressure with his tactical kicking, but Elsom said poor defence allowed the Stormers to score their tries.

Waratahs started well and took the lead through a penalty by Brendan McKibbin, but Stormers produced a good backline move from a line-out in the opposition 22, with full-back Joe Pietersen taking the final pass to score in the left corner after 17 minutes.

Pietersen landed a penalty goal before another attack from a line-out, after the Stormers opted to kick for touch instead of goal when awarded a penalty, resulted in a try from hooker Tiaan Liebenberg.

A close-range penalty by fly-half Peter Grant gave the Stormers a 16-3 half-time lead, but the Waratahs reduced the deficit to three points with a converted try by centre Rob Horne and a penalty by McKibbin in the first seven minutes of the second half.

Another Grant penalty gave Stormers some breathing space and neither side could score in the last half hour.

The home team's stuttering second-half performance came a week after fellow South Africans Central Cheetahs came back from a 16-0 deficit to score 14 unanswered points against the Cape team.

The scorers:

Stormers:
Tries: Pietersen, Liebenberg
Pen: Pietersen, Grant 2

Waratahs:
Try: Horne
Con: McKibbin
Pen: McKibbin 2

Stormers: 15 Joe Pietersen, 14 Gio Aplon, 13 Juan de Jongh, 12 Jean de Villiers (c), 11 Bryan Habana, 10 Peter Grant, 9 Dewaldt Duvenage, 8 Jebb Sinclair, 7 Rynhardt Elstadt, 6 Siya Kolisi, 5 Andries Bekker, 4 Eben Etzebeth, 3 Brok Harris, 2 Tiaan Liebenberg, 1 Steven Kitshoff.
Replacements: 16 Deon Fourie, 17 Frans Malherbe, 18 De Kock Steenkamp, 19 Don Armand, 20 Louis Schreuder, 21 Burton Francis, 22 Gerhard van den Heever.

Waratahs: 15 Bernard Foley, 14 Tom Kingston, 13 Rob Horne, 12 Adam Ashley-Cooper, 11 Atieli Pakalani, 10 Berrick Barnes, 9 Brendan McKibbin, 8 Dave Dennis, 7 Chris Alcock, 6 Rocky Elsom (capt), 5 Sitaleki Timani, 4 Dean Mumm, 3 Sekope Kepu, 2 John Ulugia/Tatafu Polota-Nau, 1 Benn Robinson.
Replacements: 16 Josh Mann-Rea, 17 Jeremy Tilse, 18 Kane Douglas, 19 Jono Jenkins, 20 Wycliff Palu, 21 Sarel Pretorius, 22 Daniel Halangahu.