Spain's Fernando Alonso warned Ferrari still had their work cut out to stay competitive this year despite his masterful victory at the rain-soaked Malaysian Grand Prix. Alonso said the team were labouring "day and night" to improve the cumbersome F2012, which despite its faults was manoeuvred to perfection around sodden Sepang by the two-time world champion for his 28th victory. The win, after a 51-minute rain suspension and a thrilling victory chase from Sauber's Sergio Perez, was a major surprise after Ferrari struggled in pre-season testing and at the year's first race in Australia. And the 30-year-old from Oviedo said the result changed nothing for Ferrari as they strive to match favourites McLaren and reigning champions Red Bull, as well as newly competitive Mercedes. "At the start of the season we've had some problems with the car and some lack of pace but we're working on that. We're working day and night. Ferrari has proved over 60 years that we're able to win," Alonso said. "The win has changed nothing in our approach for the coming weeks. In the coming races we'll have an aggressive approach we need to bring updates for the race because we're far behind." Meanwhile rival boss Peter Sauber strenuously denied Perez, a product of the Ferrari Driver Academy who is seen as a future member of the Italian marque, was under team orders not to pass Alonso in the dying laps. Sauber technicians were heard frantically urging Perez to preserve his second spot as he hunted down the Spaniard before dramatically running off-course with six laps to go. But the principal of the Sauber team, which runs Ferrari engines, said there was "100 percent... no discussion about the position" with the Italian squad. "We told him, be careful -- we need the result -- because behind us, all of our competitors scored points," Peter Sauber told Autosport.com. "(It was because) we needed the result, not the position, so there is some misunderstanding. Behind us our competitors, all the midfield teams, scored points and it was so important that we kept the result not the position." HRT's Indian driver Narain Karthikeyan was also in the firing line after a late collision punctured the rear wheel of reigning world champion Sebastian Vettel, leaving him out of the points. "Some people need to look more where they are going," Vettel fumed, and then reportedly added to German media: "As in real life, there are a few cucumbers on the road." Karthikeyan had earlier been rear-ended by McLaren's Jenson Button in an incident that left last week's winner finishing way down in 14th.