Lin Dan made it four wins out of five for his country at the China Open on Sunday, but he needed seven match points before beating his teammate Chen Long in a see-saw match in the men\'s singles final. Lin was full of confidence after his victory in the semis over tournament first seed and his arch rival, Lee Chong Wei of Malaysia, but he had to work hard to wrap the title up in two games, 21-17, 26-24. \"I felt quite relaxed after yesterday\'s match. I didn\'t think too much about today... because the gold medal would belong to China, but in the latter half of the second game I was not so patient because victory was so close\" Lin said. Lin also admitted his win over Olympic champion Lee Chong Wei the day before had taken its toll. \"Yesterday\'s match gave me more pressure... In case there would be a third game I would not have the obvious advantage. Anyway, yesterday\'s match cost me a lot of strength\", he said. Asked how he felt about becoming the best in the world, Lin refused to be complacent: \"I never think there is a best player. There\'s always a better player.\" His defeated teammate Chen Long remained positive about his performance: \"I have tried my best to compete this match I think I did a good job. I always try to keep calm in my heart and to play the game in a more relaxed way.\" The home crowd in Shanghai cheered victories in four of the five competitions on finals day. In the women\'s singles final, China\'s Wang Yihan won a bittersweet victory as her opponent Wang Xin pulled out of the match in the first game with a sprained knee, with Wang Yihan ahead 18-12. \"At about 15 minutes when I tried to receive a slam from Wang Yihan I felt my knee which was already hurt getting worse,\" Wang Xin explained, \"to avoid further hurt... and ensure the future competitions I decided to quit the game.\" \"If Wang Xin didn\'t get hurt we could have put on a very exciting game,\" said the former world champion, who dismissed questions about whether she could still savour her win in Shanghai. Women\'s doubles first seeds Wang Xiaoli and Yu Yang of China completed a Grand Slam winning of all five Super Series contests, as they defeated teammates Tang Jinhua and Xia Huan 21-11, 21-10. In the mixed doubles, top-seeded pairing Zhang Nan and Zhao Yunlei from China beat the third-seeded Danes Joachim Fischer Nielsen and Christinna Pedersen, 21-11, 21-14. However, Denmark did manage to spoil the Asian party, as third seeds Mathias Boe and Carsten Mogensen took the men\'s doubles crown, beating Korean fourth seeds Ko Sung Hyun and Yoo Yeon Seong, 21-17, 21-13. The China Open in Shanghai is the last of 12 Super Series tournaments. Players competed for $350,000 in prize money and points which will count towards a ranking that will enable them to compete next month at a finals competition in Liuzhou, China, December 14-18.