Alexandra and Roman Zaretski will look to continue their steady improvement when they perform their compulsory dance at the World Championships in Gothenburg on Tuesday. The Zaretski's finished their first ever World Championships in 20th position two years ago and came in 14th place at last year's event. Earlier this year, the Israeli duo finished in a career best eighth position at the European Championships. Also Tuesday, Israel's Hayley Anne Sacks and Vadim Akolzin, and Ekaterina Sosinova and Fedor Sokolov, begin their participation in the pairs competition. On Wednesday, Tamar Katz, who finished last years World Championships in 23rd position, competes in the ladies short program and on Friday Maxim Shipov will make his debut in the event in the men's competition. Meanwhile, Japan is aiming to become the first country since Russia in 2002 to win gold in both the men's and women's events when its figure skaters head to this week's Worlds. In a star-studded team, Mao Asada, Miki Ando and Yukari Nakano all look strong on the women's side, while Daisuke Takahashi is peaking at the right time. Irina Slutskaya and Alexei Yagudin won the men's and women's events at the 2002 worlds in Nagano. Asada is coming off an impressive performance at South Korea last month where she won the Four Continents, but will head to the March 18-23 championships, without coach Rafael Arutunian, who was also absent in Korea. Arutunian previously coached Michelle Kwan. Asada has trained under Arutunian in the United States since 2006, but decided to move back to Japan this year. Japanese media reported last month that she will seek a new coach after the world championships. Asada's main rival, South Korean Kim Yu-na, missed the Four Continents with a hip injury. Kim successfully defended her Grand Prix Final title in December and a return to action at the worlds would set up the latest chapter in the rivalry between the 17-year-old Asian dynamos. "It's good to have a rivalry," Asada said. "We want to continue to have good performances and motivate each other." Kim is expected to take part in the worlds, but whether she will be fully recovered from her injury is a big question mark. Asada has been in this position before. She was favored at last year's worlds in Tokyo but faltered in the short program where she finished fifth. She won the long program but had to settle for second overall. Asada was cautiously optimistic about her chances in Sweden. "Last year I came second in the world championships and I am working hard and training hard," Asada said. "This time round I would at least like to match that rank and hopefully even do better." Ando is the defending world champion but hasn't won a competition this year and has shown a tendency to be inconsistent over the years. After a disappointing 15th-place finish at the Turin Olympics, Ando won the worlds on home ice last year but blew a chance for gold at the Four Continents and settled for third place behind Canada's Joannie Rochette. Her performance at the NHK Trophy at Japan in December was indicative of Ando's recent problems. Trailing Italy's Carolina Kostner by less than a point going into the free skate, Ando put on a performance that resembled her outing at the Turin Games, falling twice, touching the ice another time and botching a triple combination jump on the way to a fourth-place finish. The NHK result cost Ando a chance to qualify for the season-ending GP final. Asada made the final but showed her inconsistency by missing an element and ended last in the short program. Asada then rallied to win the free program but finished second to Kim overall. Still, Ando is capable of winning on the big stage as she proved a year ago in Tokyo. Nakano is fifth in the world rankings and has consistently been doing triple axels. On the men's side, Takahashi appears to be hitting his stride at the right moment. The 2007 world silver medalist set a total points record to win the Four Continents after nailing two quads. "I definitely want to continue the momentum at the world championships," Takahashi said after winning the Four Continents. "Winning the world championships is something I've had my eyes on for some time." How Takahashi finishes in Sweden will have a lot do with the condition of defending men's world champion Brian Joubert and Stephane Lambiel of Switzerland, a two-time world champion. Joubert battled health problems over the past season. At the European Championships in Zagreb he finished third behind surprise winner Tomas Verner of the Czech Republic. Lambiel beat Takahashi in the GP final but has struggled to regain the form he showed to win back-to-back world titles in 2005 and 2006, and the Olympic silver medal. Takahashi will be bidding to become the first Japanese to win gold in the men's program.