Sir Alex Ferguson declared himself satisfied with Manchester United's goalless draw against Sunderland following an improved defensive performance.The Red Devils may have failed to win on the road for a fourth consecutive Premier League away game, but Ferguson preferred to take the positives.Whereas United's previous three matches on the road this season have seen them score seven goals and concede seven in total, the trip to the Stadium of Light ended in stalemate.Sunderland dominated for long periods, especially in the first half, and Ferguson was delighted to keep a clean sheet.He told Sky Sports: "I think you've got to give Sunderland credit, their home record this season is fantastic. "We've had to defend really well and that is the pleasing thing for me.The back four were fantastic."