Milan must keep their guard up when they host impressive Serie B leaders Sassuolo in a Coppa Italia last-16 clash on Tuesday, coach Paulo Fonseca has said.

Milan start their cup campaign against a Sassuolo team who are in good form after being relegated from Serie A last term, ending 11 consecutive seasons in the top flight.

"For me they are not a Serie B team, they have a lot of players who are on a Serie A level," Fonseca said in an interview for Milan TV on Monday.

"There is not only [striker Domenico] Berardi, who has shone in Serie A. They beat Lecce 2-0 in the previous round, who are a Serie A side. They're top of the table, they're a strong team.

"We've analysed them well. I told the players to expect a difficult match against a team that, for me, should be in Serie A."

Sassuolo, who are three points clear of second-placed Pisa after 15 matches in Serie B, have only lost at home to Cremonese this season and have gone unbeaten in 11 games since.

Milan, meanwhile, sit seventh in Serie A, 10 points off leaders Napoli with a game in hand.

"Milan haven't won the cup in a while. We need to have a clear ambition in this competition," Fonseca said.

"But we don't look too far ahead. If we are to have aspirations of making it to the final, which must be our goal, we have to win tomorrow."

Five-times Coppa Italia winners Milan last lifted the trophy more than 20 years ago in 2003.

The Portuguese coach said there will be changes to the starting lineup for the game after Milan's 3-0 home win over Empoli in Serie A on Saturday, and ahead of their next league fixture at second-placed Atalanta on Friday.

"We played two days ago. If we don't manage the team and the players well we could have physical problems, and we don't want that," he said.

"I have faith in all the players. But obviously, there will be some changes but always with the aim of winning the match."

Some of the changes are due to health issues.

"Mike Maignan will not be there due to dental surgery. Theo [Hernandez] will also not be there due to a foot issue. The others are all ready to play," Fonseca added.