MUNICH, Aug 15 (Reuters) - Lionel Messi scored a spectacular volley five minutes from time to give Barcelona a 1-0 win over Bayern Munich in a friendly at the Allianz Arena on Wednesday. The Argentine international smacked the ball just inside the post from the edge of the area to leave goalkeeper Michael Rensing helpless and settle a match marking the retirement of long-serving Bayern midfielder Mehmet Scholl. Bayern won their first match of the Bundesliga season 3-0 at home to Hansa Rostock last weekend. They are in action away to Werder Bremen on Saturday. Barcelona begin the Spanish league season with an away match against Racing Santander on the weekend of Aug. 25-26.