Claims that Carlo Ancelotti's men lost their balance with the close-season departures of Angel di Maria and Xabi Alonso have been strengthened by a spluttering start to 2014-15.
Having begun this term with a Supercopa de Espana loss to neighbours Atletico, the European champions appeared to be back on track when easing past Cordoba 2-0 in their La Liga opener.
However, that game ended in a shock 4-2 defeat, made worse when Atletico - who they beat in the Champions League final last season - left the Santiago Bernabeu with a 2-1 triumph on Saturday.
Real can at least now turn their attentions to Group B of European club football's elite competition as the Swiss champions come to town.
Leading the line for Ancelotti's men will be Cristiano Ronaldo, who scored in the Madrid derby to suggest he has fully recovered from a knee problem.
However, they head to Madrid following a disappointing 3-1 loss at Grasshopper on Saturday.
That was their second loss of this term, with St. Gallen the only other team to beat them.
Basel, who were eliminated during the group phase of last season's competition, have never progressed beyond the round of 16, which they reached in 2011-12.
