"It was not a great performance but it was necessary to make those changes as Rio Ferdinand is doubtful for Sunday with a back problem," said Ferguson. "I had to find out about Gerard Pique. We've got great confidence in the lad and he's come through very well.
"They are all top players so you have to put your faith and trust in them.
"At times we were a bit relaxed in the second half but when we speeded up the game and played with great penetration at times we could have scored a few more goals."