Liverpool will return to the Champions League group stages after a three-year absence from the competition and Mignolet said the team were focusing on the positives.
"We have to take the first 20 minutes and how we played before the international break and take it into the next game," Mignolet told British media.
"Of course we can't neglect the performance after that - we have to keep it in mind - but we have another game midweek when we can prove ourselves again.
"That's probably a good thing, the game comes early and we can put things right, change it again."
Senegal international Mane, who will serve a three-match domestic ban after receiving a direct red, was likely to feature in the mid-week game while Brazilian playmaker Philippe Coutinho could make his first start of the campaign.
Coutinho missed Liverpool's opening league fixtures and their Champions League qualifiers due to a back injury but featured in Brazil's 2018 World Cup qualifying matches.
"We thought it best to give him three or four days proper training and then he'll be available for us, which is very good news," Klopp told the club's website. (www.liverpoolfc.com)
"Phil is a fantastic player, and hopefully we can use him as quickly as possible."
Liverpool will host Burnley at Anfield in their league match on Saturday.
(Reporting by Aditi Prakash in Bengaluru; editing by Sudipto Ganguly)
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