Son Heung-Min is in a serious dip in form right now.
In his last three outings for Tottenham Hotspur, the South Korea international has been remarkably poor.
And that is a major problem for Spurs, with Harry Kane injured.
Indeed, since his goal against Burnley in a 5-0 win, he has been remarkably limited under Mourinho.
Per WhoScored, he has had an average rating of 5.95 across his last three outings, against Wolves, Chelsea and Liverpool.
Versus the Blues, of course, he was sent off and missed clashes with Brighton & Hove Albion, Norwich City and Southampton as a result of that suspension.
However, those last three outings have seen him fail to score a goal, register an assist or lay on a key pass.
He did complete six dribbles across the three games, but he was also unable to win a tackle, while he has been dribbled past on five occasions.
As a player who could fill the void left by Kane, he has shown few signs that he is ready to step up.
Against Liverpool, in particular, he did have four shots on goal but the majority of them were speculative efforts, while one effort saw him sky a shot from close-range despite being one-on-one with Alisson Becker.
Son needs to get back to being an excellent finisher.
He has scored 10 goals this season in all competitions but, on many occasions, it has appeared that he prefers an instinctive finish over an effort where he has time to think.
No clues whatsoever: Which seasons do these iconic Spurs images belong to?
That was true against Liverpool, as he spurned a major chance, and he really needs to get back to his finishing training.
With Kane out until April, Spurs need players to step up and start scoring goals.
Son is the obvious candidate to do that but his recent form is a worry; he must improve in the coming weeks.
Meanwhile, Spurs fans have hammered one man for his display against Liverpool.