The Uruguayan came on in the 77th minute before stealing the show with two brilliant finishes, his first Premier League goals since April, when he scored against Leeds United.
The 24-year-old, who appeared to have dropped down the pecking order among Liverpool's offensive talents, stole the thunder of Newcastle winger Anthony Gordon, who looked poised to break his club's 13-game league winless streak against Jurgen Klopp's side.
Trent Alexander-Arnold was lucky to stay on the pitch after pulling down Gordon, but he gave Newcastle the lead in the 25th minute when he miscontrolled the ball, enabling Gordon to sprint onto it and slot it past Alisson Becker.
Just over two minutes later, Van Dijk was sent out for fouling Alexander Isak on the edge of the box, and the VAR backed up his on-field judgment.
Darwin Nunez's double sees 10-man Liverpool makes an outstanding comeback against Newcastle 🤩🤩
— 12thkhiladi Football (@12k_football) August 27, 2023
FT: NEW 1⃣-2⃣ LIV #newliv #PremierLeague pic.twitter.com/MgnyHsTtnD
In the 36th minute, Alisson made a superb stop to knock Miguel Almiron's thunderous volley into the crossbar, sparking a spell of control from the home side.
As Newcastle took advantage of having an additional man, Almiron shot another good opportunity over the bar five minutes into the second half, and he struck the post in the 76th minute.
Nunez's entrance changed the game, as he equalized after Sven Botman fluffed his lines, allowing Nunez to rocket the ball across Nick Pope and in at the far post.
Nunez scored again three minutes into stoppage time with a nearly identical second to leave the home crowd stunned as the visitors, backed by Klopp, celebrated loudly on the field.