(Reuters) - Bayern Munich still have room for improvement and must up their game on Saturday at unbeaten league leaders Bayer Leverkusen, who have been playing close to their performance limit, said Bayern coach Thomas Tuchel on Friday. Champions Bayern, chasing a 12th consecutive league title, are in second place in the Bundesliga, two points behind Leverkusen, who are undefeated in all competitions this season for a 30-game unbeaten run. Bayern, who are on 50 points, 10 ahead of third-placed VfB Stuttgart, have lost twice in the league this season. Next week Bayern travel to Italy's Lazio for their Champions League round of 16 first leg. We have almost as many points but they are very close to their performance limit.