Bayern Munich head into Europe buoyed by results, with 10 points from their first four league games, and confident in their current squad despite no big-name signing this summer.
RB Leipzig, last season's Bundesliga runners-up, have lost three of their first four league games after Saturday's 4-1 home defeat to Bayern Munich.
Having made 18 appearances for Barcelona last season, Moriba, 18, signed a five-year deal for Bundesliga club Leipzig on Tuesday.
Sabitzer, 27, scored 52 goals in 229 appearances for Leipzig but was out of contract next June.
Dortmund compensated for the departure of Jadon Sancho to Manchester United by signing Donyell Malen from PSV Eindhoven.
Timo Werner scored a brace as RB Leipzig took a big step towards the Europa League last-16 on Thursday with a 3-1 comeback win at Serie A leaders Napoli.
Both Napoli and Juventus turn their focus back to their duel at the top of the Serie A league after a week of mixed fortunes in European action for Italian teams.
Liverpool-bound Naby Keita has hit the headlines for allegedly using a forged driving licence in Germany, but he is RB Leipzig's midfield engine who one day hopes to play for Barcelona.
Borussia Dortmund's five-point lead at the top of the table evaporated within a week after losing 3-2 to RB Leipzig.
Hasenhuettl said that his players had been cautious as they made their first foray into Champions League football.
Tielemans levelled a minute after Emil Forsberg's opener for RB Leipzig to salvage a 1-1 draw for French champs Monaco,
Backed by energy drinks giant Red Bull, Leipzig began climbing Germany's football pyramid in 2009.
It was an important win for Leipzig who play in the Champions League for the first time at home to Monaco on Wednesday.
Slovenia midfielder Kevin Kampl will replace Guinea international Naby Keita, who will switch to England with Liverpool.
Guinea international midfielder Naby Keita will join Premier League giants Liverpool next year after the English outfit agreed a reported club record deal of 48 million pounds.