He sat out last night’s game against Benfica, and will also miss the club’s Premier League matches against Sunderland and West Bromwich Albion.
Santon suffered a hamstring problem in last weekend’s 1-0 win over Fulham.
Alan Pardew: “Davide will be out for three games – at least."
However, Massadio Haidara started against Benfica at St James’s Park, and Ryan Taylor – who was fielded at left-back in the first few months of last season – is closing in on his comeback from a cruciate ligament injury.