And he came in for special praise from his manager after Saturday's 6-0 Anfield rout of Derby County.
Benitez told Liverpool's official website: "Arbeloa has done a good job for us so far. He is a young, fit boy and we know he is only going to get better in the future.
"He wasn't used to the left-back position at all but he has come in and performed very well. When you look how well he did on his debut for us up against Lionel Messi in Barcelona then you can see he is a player with ability.
"His best positions are in the centre or on the right, so it shows his quality that he can come into a new team and adapt in a different role.
"We've had international breaks and some problems with injuries this season and so we've used players who have been working with us and who are fit. He's taken the chances he has been given very well.
"We're very pleased with him but he can still improve. He needs to keep working hard and if he maintains his form then I'm sure he'll play many more games for us this season."