Manchester United is messed up by inconsistency this season and has to put together a full 90-minute performance to get away from the Champions League game in Juventus later on Wednesday, said Ryan Giggs.
United has lost 1-0 to Italian Old Trafford champions last month.
And while they have won Everton and Bournemouth in their two fights since then, Giggs said they still blow hot and cold.
"I was really impressed with United in the last four or five games, especially the second half," said Giggs, who won two Champions League titles at United.
"But I do not know what it is, as a fan of the United Kingdom, you scratch your head, they have proven they can give someone a game, but if you do not show up for 45 minutes, you will not win.
"You have to show up for 90 minutes and United has the players. It was second best the next week, but I think it will be closer on Wednesday."