Sportal.co.nz 06.Apr.2012Getty Images
Cowan will join Anton Oliver, who played 127 games between 1996 and 2007, in the 100-club in a match which could define whether the Highlanders have a realistic chance of making the play-offs.
The Stormers are the only team in the competition with a perfect record, five from five, while the Highlanders have won five from six.
"It's not about me, it's a top of the table clash and that's the big challenge for us," Cowan said.
"It's been a while since we've been one of the top teams, hasn't it? We played these guys (the Stormers in Cape Town last year (the Stormers won 18-6) and they were pretty tough. They're a well-drilled side.
"We were disappointed with our performance last year and it's good to get another chance against them. I'll put my best foot forward, whether I'm starting or off the bench, and I'll get stuck in as I always try to do. It will be an honour to be alongside Anton with 100 games."
Cowan, 30, who has played 51 tests for the All Blacks and 94 games for Southland, said he would be proud to achieve the milestone.
"I'm pretty loyal to my franchise and province and it's something I'm pretty proud of. It's been a hard slog and there have been some tough times but the support I've had from the Highlanders and Southland has been fantastic. They've always been behind me and I cherish that."
Cowan made his Super debut against Transvaal in Johannesburg in 2004, coming on as a replacement wing, but he soon established himself as the No.1 halfback.
He has played in many memorable games and he singled out the win over the Bulls in Pretoria last year - which broke a long winning streak by the Bulls - as one of the most memorable.
He has had many partners in the No 10 jersey, the most prominent Tony Brown, Nick Evans, Colin Slade and Mile Delany.
"I've always given my all. I've always worn my heart on my sleeve. I guess it's who I am."
Cowan has been overtaken in the pecking order by the in-form Aaron Smith this year but he said he remained committed to the franchise and would play whatever role coach Jamie Joseph asked of him.
There is speculation linking Cowan to English club Gloucester but Cowan said that was in the future.
"My sole focus is the Highlanders," he said. "I'm off contract at the end of the year and my manager is looking around but at the moment I just want to concentrate on us finishing as high on the table as possible."