Madrid, Oct 2 : Real Madrid, Real Sociedad and Sevilla all face vital UEFA Champions League games away from home on Tuesday, with all of them having injury problems in their defence. Nacho Fernandez and Antonio Rudiger are Real Madrid's only fit central defenders for their visit to play Napoli, with Eder Militao out for the season and David Alaba suffering a groin strain, Xinhua reports. After their dramatic injury-time win over Union Berlin in their opening group game, the visit to Napoli will be vital to decide which of the two strongest sides in the group is likely to finish top and assure a more comfortable passage in the last-16. Real Sociedad travel to play Salzburg after a 3-0 win in the Basque derby on Saturday night, but that win came at a price, with Kieran Tierney suffering a hamstring injury, while Robin Le Normand was substituted after suffering muscle fatigue and almost certainly won't start. A home draw against Inter Milan has put some pressure on the side from San Sebastian, who need to avoid defeat in Austria in what looks like a tough and even group. Sevilla's draw at home to Lens in the first round of group games has also complicated matters for Jose Luis Mendilibar's side, although they will have Marcos Acuna available to face PSV Eindhoven. Former Sevilla striker Luuk de Jong will be PSV's main threat, but Mendilibar travels with Erik Lamela, Marcao and Tanguy Nianzou all doubtful of starting, while Mariano Diaz is out with a muscle problem. /IANS