Manchester United goalkeeper Edwin van der Sar wants a cleansheet against Valencia.
Completing an entire qualification group without conceding would represent a record, which Van der Sar is quite pleased about, even if he acknowledges stiffer tests await.
"So far we have not played against the biggest teams in the Champions League. Maybe that has something to do with it," he said.
"When you start playing a higher standard of opposition it is going to become more difficult."
