"So for tomorrow night, they will probably not be ready."
Premier League holders and six-time European kings Liverpool welcome Midtjylland, who made their Champions League debut in last week's 4-0 home defeat to Atalanta, to Anfield for a Group D fixture on Tuesday.
Reds defender Matip has been out since the Merseyside derby on October 17 while Thiago suffered a knee injury towards the end of the draw at Goodison Park.
Midfielder Keita, back in training after a negative coronavirus test, has not played since coming off at half-time in the 7-2 hammering by Aston Villa just before the international break.
Midtjylland were only founded in 1999 but Klopp downplayed suggestions of a 'David against Goliath' fixture.
"We don't see Midtjylland as a small club, we see Midtjylland as a proper challenger in this group," he said.
"No-one is part of the Champions League because they are nice cities, they are in the Champions League because they earned the right the year before," the German added.
"There are no small teams in the Champions League, there are only teams who show how big they are on the pitch, not in the press conferences before games."