Inter Milan's acquisition of Eder has come too soon for AC Milan as the struggling Serie A giants continue their quest for European football, says coach Sinisa Mihajlovic.

Inter beat Leicester City to the signing of the Brazil-born Italy international from Sampdoria on Friday in a bid to salvage what, until recently, appeared to be a title-winning season.

With one win and four goals scored in their past five league outings, Inter have slipped to fourth at six points behind leaders Napoli.

The second 'Derby dello Madonnina' -- as the fixture is known -- of the season comes late on Sunday with Milan, who sit 14 points adrift, desperate for the win that would inject life into their bid for European football next season.

For Mihajlovic, Eder's arrival at their bitter rivals has come a couple of days too early.

"Eder is a great player and a fantastic signing for them but I hoped the transfer went through after the derby on Monday!" he told media.

While Eder is expected to start for Inter, there will be no place in Milan's starting line-up for Mario Balotelli, who marked his return from injury with the winner from the spot in a 1-0 Cup semi-final win over Alessandria in midweek.

Both Balotelli and German-born Ghanaian forward Kevin-Prince Boateng will start from the sidelines, with Carlos Bacca and M'Baye Niang primed to start after fellow striker Luiz Adriano suffered a knock to the ribs in training.

"I played Balotelli during the week because everyone is good at saying they are match-fit, but then you see differently on the pitch. Balotelli and Boateng aren't fit enough yet to play a full match," added Mihajlovic.

"Luiz Adriano took a knock to the ribs... he's in pain and it's unlikely we will have him tomorrow."

Inter won the opening derby of the season thanks to Fredy Guarin's late strike and a second successive victory, said coach Roberto Mancini, would mean more than just three points.

"Winning the derby is always a boost for morale and confidence. Like any match it's worth three points and it's important for us so that we can stay up there with the leading pack," said Mancini.

The Italian last week mocked his strikers after a series of glaring misses, claiming: "At 50 years old, even I would have put some of them away."

But a day ahead of the derby, Mancini changed tack: "January is a strange month for everyone. You can have dips in form for many reasons and it happens to all teams.

"Hopefully we'll get out of this rut quickly. We have to keep working hard - that's what got us up to the top in the first place."

Eder hit 12 goals for Sampdoria to sit in joint second place in the Serie A charts alongside Juve's Paulo Dybala, both players nine goals behind runaway leaders Gonzalo Higuain of Napoli.

Mancini added: "He can come in very handy but we can't expect him to come in and instantly change everything by himself.

"He'll need a bit of time to settle in. Eder is an extra option as he can play anywhere up front and he does it well."