The Brazilian samba was alive and well as Gustavo Kuerten stayed focused - quite literally - on winning the Salem Open after reaching the quarter-finals on centre court yesterday. Kuerten, who is near-sighted, was playing without his contact lenses but he said he sees better in the daytime and it showed as he carved out an emphatic 6-2, 7-5 victory over Armenia's Sargis Sargsian. 'I have problems playing night matches because I cannot see the ball and lines so well. For me, it doesn't really make any difference whether I wear my contact lenses or not during the day,' said world number one Kuerten. 'I have always had problems seeing things at night, even watching movies when I have to read the sub-titles, but in the bright sunshine, I can see better. During the night it is much more difficult to make line-calls because I cannot see so well,' he said. Kuerten, who fought off American qualifier Vincent Spadea in three thrilling sets in his opening match, is enjoying his world number one status. Although he would not say it felt better than winning a Grand Slam tournament, he said it was still good to know that 'you're the best in the world for the year'. 'It's the best you can get being the world number one player,' he said. Asked whether the feeling was better than winning the French Open, he replied: 'It's difficult to say whether it's better this or better that. It's enjoyable and it's nice to be number one.'