US star Ryan Lochte said he hoped to maintain Michael Phelps\'s golden legacy as swimming\'s new torch-bearer as he zeroed in on a final flourish at his breakthrough world championships. Lochte, who for once has eclipsed the illustrious Phelps with four gold medals and the meet\'s only world record, on Sunday said he was \"just trying not to mess it up\" after taking the mantle as the sport\'s biggest performer. \"What Michael did for the sport of swimming, I don\'t think anyone can do again,\" Lochte said. \"I\'m just trying not to mess it up. I mean, we can do our part. Hopefully, a lot more people will get to love the sport like we do.\" Lochte qualified quickest for Sunday\'s 400m individual medley final, and he is expected to combine with Phelps in the 4x100m medley relay which will round off the 16-day aquatics championships in Shanghai. The United States are runaway leaders on the swimming medals table with 12 golds, followed by China with four and Brazil on three, with Australia on two titles heading into the final day. \"I still have to focus on one more event here. After that I will focus on the London Olympics. But right now I\'ve just got to focus on the 400m medley,\" Lochte said. The United States swept Sunday\'s qualifying heats as Elizabeth Beisel topped timings heading into the women\'s 400m individual medley final, and their men\'s swimmers were fastest for the 4x100m medley. Later on Sunday, Chinese sensation Sun Yang, 19, will mount an assault on Grant Hackett\'s 10-year-old 1500m record as he starts hot favourite to add to his 800m crown and 400m silver. And Liam Tancock will hope to end Britain\'s stop-start campaign on a high as the defends his title in the 50m backstroke.