The experienced Spanish midfielder is one step closer to his comeback after resuming squad training again after a lengthy absence following both groin and foot injuries
The Spain international has not featured for Carlo Ancelotti's side this season after undergoing surgery on both a groin injury and a broken metatarsal during the summer.
Alonso had cooled talk of an imminent return last week, but the former Liverpool midfielder took part in a full session ahead of Wednesday's Champions League match versus Juventus.
Although the 31-year-old is unlikely to feature against the Serie A champions, a return against Barcelona at the weekend could now be a realistic goal for Alonso.
Madrid were further boosted as Sergio Ramos, Karim Benzema and Fabio Coentrao all joined in training after the trio sat out a session on Sunday.
The Bernabeu outfit sit top of Group H with six points from their first two fixtures and will be looking to make it three wins from as many games against Juventus on Wednesday.