Inter beat Lazio 2-0 on Wednesday (Thursday AEST) to win the Italian Cup, adding to the Serie A title they clinched with three rounds to spare.
Not since Jose Mourinho led Inter to a treble in 2010 — including the Champions League trophy — had Inter won the league and cup in the same season. Inter coach Christian Chivu, who is quickly making a name for himself in the managerial ranks after helping Parma avoid relegation last season, played on the 2010 team.
"What mark would I give Chivu? Ten out of 10," Inter captain Lautaro Martinez said after the final.
Chivu is in his first season at Inter after replacing Simone Inzaghi, who left following the disappointment of the end of last season when the Nerazzurri finished one point below Serie A champions Napoli, lost in the Italian Cup semi-finals and were routed 5-0 by PSG in the most lopsided Champions League final in history.
"Doing the double is very important," Argentina striker Lautaro added.
"It wasn't easy to start again after what happened last year but we managed to have a great season in our performances, results and intensity."
Lazio initiated their own downfall, gifting Inter both goals.
Inter took the lead in the 14th minute when Federico Dimarco whipped in a corner from the right and Lazio defender Adam Marusic headed it into his own net.
The second goal, in the 35th, was the fault of Nuno Tavares as the Lazio defender was robbed of the ball by Denzel Dumfries just outside the area. Dumfries cut inside and unselfishly rolled it across for Lautaro to score one of the easiest goals of his career.
Inter had beaten Lazio 3-0 on Saturday in Serie A in a dress rehearsal for Wednesday's cup final in the same stadium in Rome.