The champagne was on ice at the iconic San Siro, with Inter ready to lift the Scudetto in the beautiful Milanese sunshine.
Marcus Thuram nearly got the party started as he went through on goal inside three minutes, though the Frenchman was smartly denied by Lazio goalkeeper Ivan Provedel, who rushed out to smother the effort.
The in-form visitors then reminded Inter of their threat, as Taty Castellanos cut in from the left to expertly find the bottom corner, only for his effort to be ruled out for an offside in the build-up.
The Nerazzurri’s sloppiness continued to plague their performance however, with Francesco Acerbi giving the ball away to Daichi Kamada, but after the Japan international found Castellanos, Yann Sommer was on hand to keep honours even.
The Inter goalkeeper had no answer for Kamada himself however, who swept home his second of the season from the edge of the area to silence the home faithful.
After a cagey opening to the second half, Inter started to generate momentum as they went in search of a leveller.
Nicolo Barella’s header was turned round the post by Provedel, while Lautaro Martinez headed against the post from Federico Dimarco’s resulting corner.
Simone Inzaghi’s men were then inches away from falling further behind when Matias Vecino - five years an Inter player - arrowed a low effort narrowly wide of the far post.
There wasn’t a great deal of urgency to Inter’s play in the closing stages, yet when it seemed as though they’d run out of ideas, the Nerazzurri struck to the relief of the home crowd.
Dumfries netted for the first time since February, towering over Adam Marušić to power home a header that prevented Lazio from confirming their place in the top-seven.
Flashscore Man of the Match: Daichi Kamada (Lazio)
