What can be used as a lining for a Guinea Pig cage?

We just bought my daughter her first guinea pig and we bought the starter kit. In the kit was cage lining, but only one bag. I went online to find out more about these little critters and found a lot of photos where people are using fleece to line the cages with. I guess it would be great because all you have to do is wash it and it would save on buying more, but is this okay for the guinea pig or does it need more lining?