The first match is important because from the first match those teams can see how they will be in the future & also serves as a foundation for subsequent matches. There are 4 matches in the first week of the Bundesliga that are interesting to me, they are the matches:
1. Borussia Mönchengladbach - Leverkusen
Last season Bayer Leverkusen won the first title in their history undefeated. They started this season with the Super Cup and made a good start. Leverkusen have largely kept their squad intact and the champions will compete with a good squad this season. The team has also strengthened with the signings of Martin Terreier, Aleix Garcia and Belocian. I already see Bayer Leverkusen as the biggest title contender this year because Xabi Alonso and his team have preserved the formation of the team. Leverkusen have a deep squad and I don't think they will struggle in the Bundesliga this season. Gladbach are also starting with almost the same squad as last season. They looked very effective in the friendlies and in the German Cup. Leverkusen will win this match despite being away. Both teams are ready for the season but Leverkusen is the more ambitious team.
Mochengladbach is also not a very weak club. They know how to fight for goals even if they can't win. So, they'll give Leverkusen a very tough fight. It is fine to go for BTTS.