Captain Siya Kolisi says the Stormers have to improve their decision-making to succeed in their quarter-final against the Chiefs at Newlands on Saturday.

The Stormers beat the Bulls 41-33 at Loftus over the weekend, but were in danger of losing the match before scoring a late try. They conceded five tries, while flyhalf Damian Willemse's goal-kicking was wayward.

Kolisi admits his side will have to up their game on Saturday.

'If there are opportunities to run the ball from our 22, we will do that. But we have to improve our kicking and decision-making. In the past, we were programmed to do certain things at certain times. We have to make decisions instinctively,' said Kolisi.

The Stormers beat the Chiefs 34-26 at Newlands earlier this year, but lost 60-21 to them in the quarter-finals last season.

'I'll never forget what happened last year,' said Kolisi. 'No one in the team wants to allow a repeat of that result. We are also a completely different side now than we were then.' 

Stormers coach Robbie Fleck said his team would have to tighten up their defence if they were to progress to the semi-finals.

'The way that we are going at the moment in terms of our attack, we are putting teams under pressure and we are scoring some good tries,' he said.

'The way that we changed our mindset this year is obviously we are playing a lot more rugby, which leads to turnover possession against us. The biggest challenge for us is being able to learn to attack and defend at the same time.

'When we do turn over possession, we've got to be able to stop their momentum or linebreaks.

'You are playing against a quality outfit in the Chiefs. They are a great attacking side and they can put you to the sword on turnover possession, which they did to us in the quarter-final last year. If we can tighten up on a few areas, I think it would be a good battle out there.'

The match kicks off at 17:00 on Saturday.

Photo: Thinus Maritz/Gallo Images