Liverpool goalkeeper Alisson is undertaking extra training sessions at Melwood as he pushes for a return to action against Manchester United on Oct. 20.

Players not on international duty have been given the week off by manager Jurgen Klopp, but the 27-year-old, who sustained a calf injury during the Premier League opener against Norwich City, has remained at the training complex to improve his sharpness.

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Goalkeeping coach John Achterberg has been working chiefly on Alisson's speed, reactions, distribution and power having spent the September break getting Brazil's No. 1 out on the pitches again to do catching, footwork and small passing drills.

The Premier League's Golden Glove winner for 2018-19 has progressed well through his recovery stages and has upped his strength with rehabilitation fitness coach Dave Rydings in the gym.

Liverpool had earmarked Alisson to be available after the October interval, but there is no longer such a strong need for him to return against struggling United if he is not yet at 100% given the performances of his understudy, Adrian.

The 32-year-old has been an excellent stand-in as Liverpool have recorded a perfect start to the league season, with eight wins from eight.

Adrian's form has allowed Liverpool to ease Alisson through the different phases of his rehab with no time constraints or pressure to be in line for contention.

Adam Lallana and Alex Oxlade-Chamberlain, meanwhile, have voluntarily ceded time off to do additional training at Melwood.

Both midfielders have been informed they will have bigger roles to play as the games continue to come thick and fast for Liverpool.