Ferguson feels United have benefited from a settled centre-half pairing of Ferdinand and Jonny Evans.
"Ferdinand's form in particular over the last couple of months has been outstanding," he said. "It does tell you that when you play two partners together for longer periods rather than chop and change it makes a difference. Jonny Evans has emerged through having the experience of playing with Rio, so that's been a plus for us. I'll accept 1-0 against Bilbao rather than 2-1 or 3-2 without question."