However, Dalglish has said that United will need to strengthen further if they want to improve their current position of seventh in the Premier League.
He told The Mirror: "Juan Mata is a very good player but he is not going to be able to turn everything around by himself at Manchester United.
"He has been fantastic since he has come to the Premier League and he will be invaluable. But United fans will have to be patient. Mata's going to need help. Getting Wayne Rooney and Robin van Persie back fit again will be a massive boost, too."