Nemanja Vidic won five Premier League titles and the 2007-08 Champions League in an eight-year spell at Old Trafford, but conceded injuries had forced him to call time on his career.
Nemanja Vidic joined Inter Milan on a free transfer from Manchester United in 2014 and played 28 times for the Italian Serie A club last season.
Inter Milan secured a 3-1 win over Genoa in to move up to ninth place in Serie A.
United travel to Aston Villa on Sunday for a league fixture that they have not lost since 1995, but with the champions already 13 points behind leaders Arsenal, their grip on the title is weakening.
Serbian defender Vidic acknowledges United have been well below their best so far, and he believes his defence must provide a solid foundation to allow Moyes' men to get back on track against Sunderland, who sit bottom of the table without a manager after Paolo Di Canio's sacking and still waiting for their first win of the season.
United have long been renowned for their dashing wing play, but the club's wide players have gone off the boil over the past year. Antonio Valencia no longer bursts past left-backs with the explosive pace he exhibited in his first two seasons at the club, while Ashley Young was lambasted for a careless display at City and Nani remains a model of inconsistency. Th...
The England striker has made it clear he wants to quit United after growing unhappy with his diminished role last season and Chelsea boss Jose Mourinho is determined to lure him to Stamford Bridge.
Moyes was speaking ahead of next weekend's sold-out pre-season tour match against the Australian A-League All Stars in Sydney. "I'm following probably the finest football manager that's ever lived," he said of Ferguson, who won a string of honours including 13 Premier League titles.
His absence may be connected to the treatment he needs for a chronic knee injury that has ruled him out for virtually 12 months and a fresh problem would be a major concern for Moyes ahead of his first season in charge at Old Trafford after succeeding Alex Ferguson.
Vidic, a Serb compatriot of the 2011 champion, opted for the second show court to sit with his wife Ana in the Djokovic box while his former Manchester United manager Alex Ferguson stayed on Centre Court.