The coach of South Korean swimming star Park Tae-Hwan has warned the Olympic champion against complacency after his triple gold at the Asian Games, saying tougher challenges are ahead. Park won the 100 metres, 200m and 400m freestyle events in a stunning performance in the Guangzhou pool. He also grabbed silver in the 1,500m behind China's Sun Yang. But his Australian coach Michael Bohl said that although he was proud of Park's achievements, the 21-year-old could not rest on his laurels. 'If he thinks those times are going to win next year (at the world championships in Shanghai), he's going to be mistaken,' Bohl said, according to South Korea's Yonhap news agency. 'He can be happy, but not satisfied.' Park won a total of seven medals in Guangzhou -- including a silver and two bronze in relay events to match his overall haul from the 2006 Asian Games in Doha. The Olympic 400m freestyle champion flopped at last year's world championships in Rome but Bohl has helped him get his career back on track. The Australian though said 'a stack of guys' would be ready to challenge Park after his Guangzhou successes. 'Sun Yang (of China) is improving at a great rate, and (American) Michael Phelps had an off-year, but he's going to come back with a vengeance next year,' Bohl told Yonhap. Sun only narrowly missed breaking Australian star Grant Hackett's long-standing world record in the 1,500m, smashing the Asian Games mark by more than 10 seconds in a time of 14min 35.43sec. Park was more than 26 seconds adrift. Bohl said the likes of Phelps and Germany's 400m freestyle world record holder Paul Biedermann would be motivated to train harder by Park's times. Both his 200m, in which he set an Asian record of 1min 44.80sec, and 400m (3min 41.53sec) were the quickest in the world this year and Bohl called them 'very scary and very competitive.' He said Park should focus on the 200m and 400m rather than the 1,500m and that the South Korean's 100m winning time of 48.70sec would not be competitive on the world stage. But Bohl insisted all of the races were 'good' because Park entered the Asian Games with heavy expectations after a poor year in 2009. 'Last year was a bad year, and it was an accumulation of things,' Bohl said. 'He's a current Olympic champion in the 400m.... All that pressure coming in, he handled it really well and came up with great results. It's just a credit to him.' 