Saints go to Old Trafford under new manager Mauricio Pochettino.
"I think everyone was shocked when Nigel Adkins went, but ultimately players have got a job to do and the new manager will put his ideas across and players will just get on with it," said Giggs.
"Southampton have been in decent form and on a good run; it'll be another tough game for us. They gave us a good game earlier in the season so we'll need to play well.
"Every game at this time is tough but there are no easy games in this league. You've got to perform well in every match and you want to do that for your own satisfaction and for your own form. You want to play well because it gives you confidence going into the next game."