Simone Inzaghi defended the "misunderstood" Romelu Lukaku celebrations after the Inter striker sparked late carnage at Juventus on Tuesday.

Loanee forward Lukaku restored parity with a 95th-minute penalty at Allianz Stadium, leaving Inter on level terms after a 1-1 Coppa Italia semi-final first-leg draw.

The Belgium international celebrated in front of Juve's Curva Nord, immediately prompting a confrontation with Juan Cuadrado that saw Lukaku receive his marching orders for a second yellow card.

Cuadrado, who scored the 83rd-minute opener, was then dismissed for a clash with Inter captain Samir Handanovic after the full-time whistle as tempers continued to boil over in Turin.

Inzaghi insisted Lukaku's reaction was understandable, though, as the Inter coach bemoaned losing his key forward and goalkeeper Handanovic to suspension.

Asked whether Lukaku's celebration was towards the crowd, Inzaghi told Mediaset: "Yes. This was clear, but it goes beyond this.

"I see a player who scores, celebrates, and everything happens there. Lukaku's celebration was misunderstood.

"It certainly wasn't a nice sight to see in a well-conducted and fair match until the 94th minute.

"[But] now I have to be clear-headed and think that for the return semi-final. Lukaku's celebration will deprive me of him and Handanovic."

Juve goalkeeper Mattia Perin was left far from impressed by what he deemed to be a disrespectful act by Lukaku, who appeared to shush a section of Bianconeri supporters behind the goal.

"We have to be the first to set an example, but in these games it's difficult to hold back," Perin told Sky Sport Italia.

"It's a lack of respect to celebrate under the Curva of the opposing team."

A hard-fought draw somewhat halted Inter's slide, having headed to Juve on the back of three straight Serie A defeats that have left the Nerazzurri's top-four place in doubt.

Inter are level on points with fifth-placed Roma and just six clear of Juve despite their 15-point deduction, but Inzaghi is buoyed by the support of the Nerazzurri faithful.

He said: "Our supporters are unique and incomparable. We lost a home game on Saturday, and up to the end, the Curva never left us.

"We are Inter, it's normal to expect different results. There was a call for everyone that we expect more and better. Tonight was a great response from players to the whole environment."

Goalkeeper Mattia Perin said Juventus' draw with Sampdoria left "a bad taste in our mouth" and showed where Massimiliano Allegri's side must improve.

Juventus were looking to join Napoli, Inter and Roma on six points from two games at the start of the Serie A season on Monday, but could only manage a 0-0 stalemate on their travels.

They failed to break down a Sampdoria side who lost 2-0 to Atalanta on the opening weekend of the season, and coach Allegri said his players would need to train hard ahead of Saturday's enticing tussle with Roma.

Perin said of the result: "This draw should serve as a lesson to understand which areas we need to work on. 

"Obviously, it leaves a bad taste in our mouth, but it will be an extra incentive to better prepare for the next game.

"Surely not having conceded a goal for the second consecutive matchday is an excellent sign and confirms how much good we are doing in training."

Perin also told Juventus' website: "We knew it would not be easy to come and play at the Marassi, against a team as difficult to face as Sampdoria. Now, our goal is to continue training with the same determination as we have shown up to now."

Allegri could soon have reinforcements on the way, with Barcelona forward Memphis Depay a confirmed target. Vice-president Pavel Nedved strongly hinted Juventus also have other players in their sights when he spoke shortly before kick-off at Sampdoria.

After the game, Allegri preferred to focus on the players already at his disposal, saying: "The club will take care of the market, we have to work. We have to look at the positive things, not the negative ones."

Adrien Rabiot had a goal disallowed due to Dusan Vlahovic straying offside, and Allegri said Juventus had shown "little patience" in the first half before improving after the interval.

Striker Vlahovic only managed three touches in the first half and had just nine across the full 90 minutes.

No player to take the field for 90 minutes in a Serie A game has had fewer touches since David Trezeguet had eight for Juventus against Catania in May 2008.

"We would have liked the three points, but the positive aspect is that in these first two matchdays we haven't conceded a goal," Allegri added.

"We are growing in condition and we will continue to work hard to get ready for the match on Saturday evening against Roma."