The Reds captain admitted the dismissal of John Obi Mikel could have worked against United - especially if the Blues had reached the break on level terms.
"When you play against ten men, they all get behind the ball," said Giggs.
"It can be difficult but we scored at the right time."
It was Giggs who delivered the right-wing cross for Carlos Tevez to nod home his first goal for the club as half-time beckoned.
"You get the ball into the area and hope the centre-forwards get in there," said Giggs.
"Carlos had made a great run – you’ll score loads of goals running across the near post and he managed to do that. I was really pleased to see it go in."
United's goal hero at the other end of the game was the substitute Louis Saha, who won and then converted a penalty to kill off any faint hopes Chelsea might have had of earning an ill-deserved equaliser.
“I think one-nil’s always a dangerous scoreline, even if you’re playing against ten men," reflected Ryan.
"Chelsea have got quality players that can score goals so it was really pleasing to see the second goal go in."
It was a day of firsts for United as Saha and Tevez both opened their goalscoring accounts for the season, to give the Reds their first win by more than one goal. Both reflect the strength in attacking depth that the Reds are beginning to enjoy.
“We’re getting players back now so we've got lots of options," added Ryan.
"Nani and Louis were on the bench today so we’ve got players who can come on and make an impact as well."