Berlin (AFP) - Champions Bayern Munich ended their three-match losing streak in the Bundesliga with a season-ending 2-0 win over Mainz on Saturday as Hamburg and Stuttgart avoided relegation.A Robert Lewandowski penalty and Bastian Schweinsteiger goal saw Bayern bounce back after defeats by Leverkusen, Augsburg and Freiburg since their 25th German league title was confirmed at the end of April.Poland striker Lewandowski converted a 25th minute penalty after a handball by Mainz defender Nico Bungert.Germany captain Bastian Schweinsteiger scored their second just after the break to secure the win to kick-off celebrations in Munich as Pep Guardiola's side was presented with the trophy at the Allianz Arena.There were plenty of customary 'beer showers' on the pitch as Bayern players hunted victims over which to pour huge glasses of frothing liquid after the final whistle."We've done really well to defend our title this season despite a lot of injuries and we'll celebrate tonight," said Germany defender Jerome Boateng.