Thiago and Fabinho are expected to be paired together on Wednesday to try and wrestle control from Madrid's talented triumvirate, but Klopp also has a big decision to make up front.
Champions League: Jurgen Klopp hopes change of competition will bring respite for struggling Liverpool
A sixth successive home league defeat, the latest to struggling Fulham on Sunday, left the Reds well adrift of Champions League qualification, having played more matches than the teams immediately above them.
With 11 games left, seventh-placed Liverpool are languishing four points behind Chelsea in fourth.
Arrivals in Britain from "Red List" countries are subject to 10 days' hotel confinement, which would apply to Brazilian trio Alisson Becker, Roberto Firmino and Fabinho and Portugal forward Diogo Jota.
Premier League: Manchester City beat Tottenham to extend lead to seven points; Liverpool stunned by Leicester
Pep Guardiola's side stretched their English top-flight record run to 16 successive victories in all competitions.
Premier League: Fabinho to miss Leicester City clash due to muscle injury as Liverpool’s injury crisis worsens
Fabinho has largely been used in central defence by Jurgen Klopp this season after Virgil van Dijk, Joe Gomez and Joel Matip suffered season-ending injuries.
Matip's injury is another blow to Liverpool's hopes of retaining the Premier League title.
Premier League: Liverpool suffering from 'rusty moment' reckons Jurgen Klopp after 0-1 loss to Southampton
Danny Ings's stunning second-minute goal earned three points which moved Southampton into sixth and led to Saints manager Ralph Hasenhuttl breaking into tears of joy on the final whistle.
Premier League champions Liverpool would not say how long the 29-year-old central defender would be out.
Premier League: Liverpool trying not to rush players back to action despite injury crisis, says boss Jurgen Klopp
Brazilian midfielder Fabinho, filling in for the absent Virgil van Dijk and Joel Matip in central defence, limped off in the first half of Tuesday's Champions League match against Midtjylland with a muscle issue.
Liverpool managed to beat both Dutch giants Ajax and Sheffield United last week despite missing star central defender van Dijk.
Klopp now only has two fit senior centre-backs in Joe Gomez and Joel Matip, with midfielder Fabinho providing impressive cover in the midweek Champions League victory over Ajax
Premier League: How Liverpool's three key forces came together to deliver historic title after 30 years
It took a while for Liverpool to get the right ingredients, but once they had the recipe, Liverpool FC embarked on an unstoppable, inexorable march of clinical performances that bore witness to their greatness.
Premier League: Leaders Liverpool announce pre-tax profit of $54.57 million after Champions League-winning campaign
Liverpool signed goalkeeper Alisson and midfielders Naby Keita, Fabinho and Xherdan Shaqiri during the accounting period and offered new deals to 11 players
Premier League: Liverpool boss Jurgen Klopp describes team's 25-point gap at the top of table as 'insane'
Liverpool boss Jurgen Klopp described his side’s 25-point lead at the top of the Premier League as insane after a 1-0 win at Norwich City on Saturday continued their romp to the title.
Premier League: Liverpool's Joel Matip, Fabinho in line for return from injury against Manchester United
Liverpool have been handed a double injury boost ahead of their Premier League meeting against Manchester United on Sunday with defender Joel Matip and midfielder Fabinho both fit
With fellow centre back Joel Matip also nursing a knee injury, Klopp said the league leaders had only two fit senior centre backs to choose from, with Virgil van Dijk and Joe Gomez set to play against the bottom side.
Champions League: Liverpool not the only team with injuries, we have to find a way to fill Fabinho's void, says Jurgen Klopp
Liverpool must live with the absence of the injured Fabinho and find an alternative solution to fill the gap in midfield with the Brazilian ruled out until January, manager Jurgen Klopp said on Friday.
Champions League: Liverpool's Fabinho ruled out till New Year after suffering ankle ligament injury in Napoli draw
Liverpool midfielder Fabinho suffered an ankle ligament injury in Wednesday’s Champions League draw with Napoli and will be out of action until the New Year, the Premier League club said on Friday.
Premier League: Liverpool boss Jurgen Klopp sweating over Mohamed Salah's fitness ahead of Crystal Palace clash
Egyptian forward Salah has been struggling with an ankle injury since a heavy challenge from Hamza Choudhury during Liverpool 2-1 win early last month