Former Manchester United boss Sir Alex Ferguson says Arsenal's Invincibles outstripped anything he achieved over his managerial career.

Ferguson made the claim when paying tribute to Arsene Wenger in a documentary about the former Arsenal manager.

In 2003-04 Arsenal did what no team in the top-flight had done since Preston in 1888-89 – survive an entire league season without losing.

Ferguson said: “The achievements stand above everything else."

Elsewhere in the newly-released two-minute trailer for “Arsene Wenger – Invincible", Ferguson is seen reflecting on the heated rivalry that took centre stage throughout the late 1990s and 2000s.

The Scot said: “I'm saying to myself: 'Is he looking for a war?'"