The Argentinian has been linked with a move to the Blues after a difficult first half of the season. Higuain's demeanor during matches has not been great in the last month and he has scored just once in his last 10 outings.
Leonardo did not hold back when asked about the on-loan forward, per Football Italia:
"He has to make a decision and take on his share of the responsibility. Not this continual yes, no, I'm not sure. He had a tough moment, he has to put it behind him and get to work.
"There's no point following rumours and gossip. He is here right now. Seeing as he is here, he needs to get down and actually do something for this team.
"A goal can change things, but if he is to continue here, he needs to take on responsibility."
Those comments stand out because Leonardo was adamant Higuain wasn't going anywhere and the club had no "doubts" about their forward late last month:
The 31-year-old moved from Juventus to Milan in the summer on a loan deal, with the Rossoneri holding an option to make the deal permanent. At the time there was no doubt they would use the option but his poor form and the club's issues with financial fair play have made a permanent switch less likely.
Chelsea have emerged as suitors due to their need at the striker position and the presence of Maurizio Sarri. Higuain had his best ever scoring season under the Italian tactician while the two worked together at Napoli.
According to Bleacher Report's Alex McGovern the lack of a quality striker was once again a glaring issue in Tuesday's loss to Tottenham Hotspur:
Alex McGovern @AlexMcGovern11
Thought Chelsea played really well. Same problem as usual though: Lack of striker/runs in behind and lack of a final pass. Striker and left centre-mid are the two biggest problem positions offensively, and I can’t see Barella/Paredes as solving the midfield part. #TOTCHE
Sarri has made no secret of the fact he wants the club to sign a new striker, per the Press Association's Matt McGeehan (h/t MailOnline).
Leonardo's latest comments appear to indicate Milan are warming up to the idea of a premature split, which could be good news for Chelsea.
The deal could still prove difficult even if Milan want to make it work, however. Higuain is still a Juventus player, and the Bianconeri will have to sign off on everything.
They'll be hoping for the transfer fee that was part of the original deal with Milan, and the Blues may be forced to cough up a similar fee.