Inter Milan reached their first Champions League final for 13 years as Lautaro Martinez's sole goal of the match gave them a 3-0 aggregate win against AC Milan on Tuesday.

Inter will undoubtedly be the underdogs against either Real Madrid or Manchester City in Istanbul on June 10, but the way they managed both legs of this all-Milan tie suggests they will be hard to beat.

The key moment of the night at the San Siro came when Argentinian Martinez exchanged passes with substitute Romelu Lukaku and drilled a shot from inside the penalty area that Milan goalkeeper Mike Maignan allowed in at his near post.

Martinez, Inter's captain, hailed the cohesion of his team over the two matches against their city rivals.

"What counts is the squad. I experienced it at the World Cup (with Argentina)," he said.

"It makes it easy if you have a united squad with everyone pulling in the same direction. It means you get to play these very important matches in the best possible way."

He added: "After winning the World Cup and experiencing what is the pinnacle for a player I knew we could reach this final, and we did it."

His goal effectively killed off the tie.

Trailing 2-0 from the first leg, Milan had pushed hard in the first half, spearheaded by Rafael Leao who shot across the goal and past the post with one of his side's best chances.

Maignan then superbly dropped to his knees to collect Edin Dzeko's glancing header from Hakan Calhanoglu's pacy free-kick.

Lukaku's introduction in the second half proved the spark that Inter needed to extend their lead.

Absent for much of the season with injuries and with a damaged reputation following a disastrous World Cup with Belgium, Lukaku has slowly worked his way back to his best.

The forward on loan from Chelsea immediately caused problems in the Milan defence and created Martinez's goal to guarantee their place in their first Champions League final since the last time they won European club football's biggest prize under Jose Mourinho in 2010.

"Tutti a Istanbul", the joyous Inter fans sang with the Nerazzurri now one game away from a fourth Champions League title.

Inter coach Simone Inzaghi said: "It's a dream come true. We always believed we could do it, we have had an extraordinary journey (to the final).

"What pleased me? Everything. The running, the determination, the concentration... they were very good."

Facing Inzaghi's men will be either Manchester City or record 14-time winners Real Madrid, with that semi-final finely poised at 1-1 ahead of Wednesday's decider at City's Etihad Stadium.

"We're going to have to give it our all," Martinez said.

Milan's coach Stefano Pioli was left to contemplate a harsh ending to "a terrific" run to the last four.

"It's normal to be disappointed after losing in the semi-final, especially in a derby.

"The players gave their all in both legs but Inter deserved it. They played better than us, winning both matches.

"Given our journey and what we've done over the past three years it would have been fabulous to get to the final. But we didn't make it, that's a massive disappointment." (AFP)