Giggs' status as a United legend is already assured, having won 12 Premier League titles, four FA Cups, three League Cup and two Champions Leagues during a glittering 21-year career at Old Trafford.
However, the 39-year-old has struggled to make an impact on the first-team this season, making just 10 league starts to date.
That has led to some to question whether the Welshman should hang up his boots at the end of the season, rather than sign another one-year deal that would take him beyond his 40th birthday.
When quizzed about Giggs' lack of form Ferguson defended the player, insisting that his decision to use Giggs sparingly is the main reason why he has failed to reach his usual high standards.
"How can you criticise a player that has given you 20 years?" said the 70-year-old.
"Let's be honest. He may have an off day here and there because I don't play him all the time.
"But at his age I can't afford to risk him."