Rafael has been a hit on the right back while Fabio has only had a few chances at left back as Patrice Evra is still the automatic choice.
“We are young,” Rafael told uefa.com. “Fabio’s chance will hopefully come and he will be able to show people how good he is. At the moment, we are here to learn and help the team.
“One day at a time.
“It has always been natural for us [to play on either flank] and there was really no intent on our part, especially when you think that, at one point in our careers, I was playing as a defensive midfielder and Fabio as a striker. But I totally understand that people are a bit puzzled.
“Yeah [there is friendly rivalry between us], but we love playing together. He told me the other day that I should enjoy that strike against Arsenal [in United’s last defeat back in November] because it was probably the only time in our lives that I had outscored him.”