The Arsenal legend has shared his opinion about Tottenham Hotspur.
Tottenham missed the 23-year-old through injury earlier in the season, in which time they netted six Premier League goals in five matches.
Son Heung-min initially found form and filled the goalscoring void left by the English hitman, but Vincent Janssen, an £18.5 million signing in the summer, failed to do much and still has not scored a goal for Spurs from open play.
Mauricio Pochettino's side lost 1-0 at Old Trafford on Sunday in a defeat which leaves them 10 points behind top-of-the-table Chelsea in fifth.
And Arsenal legend Henry says that Tottenham's biggest problem lies in the absence of a game-changing figure from the bench.
He told Sky Sports: "Tottenham have Harry Kane back now, but when he is not scoring in big games, who is scoring for them?
"Someone else needs to come in. Vincent Janssen has come in, and hasn't answered the call yet. He needs time.
"The problem is, Tottenham need a guy on the bench who can come on and change things."
It would appear as if the best Spurs can do this season is qualify for the Champions League, which is not much progress after achieving that last season.
It will certainly be harder this time around, given how the big boys are back on song, but they were expected to challenge for the title and it remains to be seen if that 10-point gap will lessen or increase over the coming weeks and months.