Didi Hamann has told Premier League Daily Liverpool should beware a rejuvenated Manchester United who could yet play a part in this season's title race.
Jurgen Klopp's side have a five-point lead over United heading to Old Trafford for this weekend's Super Sunday game, but their rivals are on an eight-match winning streak.
Hamann puts that down in part to Mourinho's new hands-off approach after a series of run-ins with officials and apparent public criticism of some of his own players.
And the former Anfield midfielder, whose haul of Reds winners' medals includes one for the 2005 Champions League, is not completely writing off the possibility of his pre-season tips bridging the 10-point gap to leaders Chelsea.
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"There was a time a few weeks ago when United had a seven or eight-point gap to fourth place, and the deficiency now is two points," he said. "They're in touching distance with all the other teams apart from Chelsea so Mourinho is a lot more safe.
"His behaviour was a bit erratic at the start of the season, and he took a step back for whatever reason.
"Perhaps someone at the club had a word with him and said at Man Utd he can't get away with things he may have done at other clubs. I think that's part to do with the form they've found, they look a far happier outfit.
"At the start of the season I tipped him to win the Premier League. Whether a 10-point lead for Chelsea is too much I'm not sure, but I still believe United have the most talented squad and once Mourinho's teams get going they can be very hard to stop.
"You've got to watch out for them in every competition, and in the Premier League I think they'll be a team to watch out for in the coming months."
Liverpool will be without top scorer Sadio Mane, who is away at the Africa Cup of Nations, and the Senegal forward's absence is one reason why Hamann fears for his old club this weekend.
"Mane has been one of the most influential players in the first part of the season," he said. "So I think United, who nullified Liverpool at Anfield [in a goalless draw in October] might have the edge on Sunday."