Carvajal was forced to depart in the first period after picking up a hamstring problem, with Arbeloa entering as his replacement.
A long-term injury to Carvajal would open up a spot in the team for Arbeloa, but the latter is hopeful that his teammate is only sidelined with a "niggle".
"Let's hope that what happened to Carvajal is nothing. He picked up a niggle and preferred not to risk it," Arbeloa told the club's official website.
Arbeloa is in line to start when Madrid face his former club Liverpool in the Champions League on Tuesday.