While Rafael excelled for the Reds as the team's first-choice right-back, Fabio enjoyed a season gaining further first-team experience on loan at QPR.
The pair are back together on Tour 2013 presented by Aon and relishing the challenge under new manager David Moyes.
"Pre-season is all about fitness and we've all been working hard on tour," Rafael told ManUtd.com. "We had a good summer and a good rest, but we missed playing football!
"Our week in Sydney was very productive. The facilities were great and it's a very nice country. It's been really good to work hard together in training."
Fabio echoed those sentiments and added: "It's great to be back with my brother.
"We have both matured a lot in the last year. My time at QPR has really helped me mature and I also think it helped my brother [for us to be apart]. He had a great year last season.
"As my brother said things have been going well with pre-season. The manager has the same mentality as Sir Alex - he wants to win. He is working hard and so are all the players because we want to win more trophies. Hopefully we can."