MADRID - European champions Barcelona still have room for improvement in a number of areas, coach Pep Guardiola said on Saturday before the Spanish Super Cup first leg against Athletic Bilbao. The traditional curtain-raiser to the new season sees Barca visit San Mames on Sunday to take on the team they hammered 4-1 in the King's Cup final last May. By the end of the month Barca had also wrapped up the Champions League and Primera Liga titles. "Last year we played a perfect season without playing a perfect game, because there are always things to improve on," Guardiola told a news conference. "We still have many things we could do better and this is what fills us with enthusiasm." Barca will be without a number of key players, though have included striker Thierry Henry who has recovered from the Achilles tendon problems that forced him to miss France's World Cup qualifier in the Faroe Islands. Lionel Messi is out with a thigh muscle injury picked up on international duty with Argentina and new signing Zlatan Ibrahimovic is still waiting to make his debut as he recovers from hand surgery. Defender Rafael Marquez and midfielder Andres Iniesta are also out injured. Bilbao have tasted competitive action this season, overcoming Young Boys on the away goals rule in the third qualifying round of the Europa League. They will have one eye on next week's playoff first leg at home to Tromso.