At the group's spring tasting, wine development manager Paul Bastard said sales were buoyant despite the relatively flat British wine market - and Nielsen Homescan data which he said painted a distorted picture of Co-op's performance.
"Sparkling wine and Champagne is doing well, and we're up 79.8 per cent on rosé," he said. "With rosé we've come from off the pace to 7.3 per cent market share.
"South Africa is almost double everyone else's market share - it's 13.6 per cent of our sales and the market is 7.8 per cent in total GB."
The tasting showcased many of the newcomers and special parcels available in the Co-op this spring, with an emphasis on third-party wines and not the 140 own-labels in the group's range.
Bastard said: "We're not the greatest fans of the big brands because we look for a point of difference with Fairtrade and exclusives.
"Even with Australia, if you look at the performance in the big brands, we're doing OK but not as well as some of the multiples - and in a way that is on purpose."
The tasting featured one newcomer from France - La Différence Carignan 2006 - and Bastard admitted the French category was "still causing a bit of concern".
"It's the one country where we're not particularly happy," he said. "It was interesting in Wine Relief how well Chablis did. It was our second biggest seller after our own Pinot Grigio.
"France is not easy, but we will get there."
Highlights of the tasting included Luis Felipe Edwards Reserva Sauvignon Blanc 2006 (Chile) at £5.99, Anakena Shiraz 2005 (Chile) at £4.99 and Co-op Tierra Sana Organic Tempanillo Rosé 2006 (Spain) at £3.99.
There are 465 wines in the Co-op range and the group is reporting a 6.9 per cent share of the market.