The Dutchman attacked with 5.5km remaining as he crested the Poggio, and powered solo down the descent. Filippo Ganna (Ineos Grenadiers), Wout van Aert (Jumbo-Visma) and Tadej Pogačar (UAE Team Emirates) followed in pursuit, but ultimately couldn't close the gap, which stretched out to 15 seconds.
Ganna crossed the line in second to earn his first Monument podium, while Van Aert finished in third place.
Speaking after the race, Van der Poel said: "I cannot imagine a better scenario than this one.
"I knew I wanted to place an attack at the end of the Poggio. I managed to find a small gap between Pogačar and the wall.
"This is one of the races I really wanted to win. The way I won it today is beyond expectation, I'm really happy with this one."
The Dutchman's feat comes 62 years after his grandfather, Raymond Poulidor, took his sole career Monument win at Milan-San Remo. Asked about the importance of the race, Van der Poel said: "It's one that every rider wants to win one day.
"I was really focused already on this race since I started training again after [cyclo-cross] Worlds. Tirreno[-Adriatico] wasn't as good as I expected, but I knew that I needed some race days to get to my best level and today, this was my best level, I think."
How it happened
It was an early wake-up for the WorldTour peloton on Saturday morning, as they headed to Abbiategrasso for the first Monument of the season. The 175-strong field rolled out of the town, 22km south-west of the Italian capital, and braced themselves for the long slog down to the coast.
On his Monument debut, 22-year-old Negasi Haylu Abreha made history as the first Ethiopian to compete in the event. The Q36.5 Pro Cycling rider made sure to be noticed, too, teaming up with eight others to form a nine-rider breakaway up the road.
The first 100km were predictably uneventful, with the front group forcing an advantage of around three minutes. They kept their gap over the Passo del Turchino, the climb that marks the midway point, where a touching of wheels in the pack brought 2019 race winner Julian Alaphilippe (Soudal Quick-Step) to the floor. Calmly, the two-time world champion remounted his bike, before railing the descent to rejoin the peloton.
By the time they reached the Mediterranean Sea, the breakaway’s advantage had halved. The race then thundered on, over the three capi, through the narrow Ligurian streets and towards the fabled Cipressa.
The battle into the foot of the penultimate climb is said to be one of the hardest-fought in world cycling. Tagging the day's escapees on the approach, this year, the battle was won by Ineos Grenadiers, before UAE Team Emirates bulldozed through and took up pacing duties for Pogačar.
Nobody, however, was brave enough to attack on the Cipressa. Van der Poel was the first to crest the climb, and the Dutchman led down the winding descent.
An audacious, and ultimately short-lived, attack from Nils Politt (Bora-Hansgrohe) followed on the flat. Bahrain Victorious, steered by Fred Wright, then wound up the pace onto the Poggio, with reigning champion Matej Mohorič in tow.
As it turned out, that would be the last we would see of the Slovenian. His compatriot and two-time Tour de France winner Pogačar was guided through to the front by Tim Wellens (UAE Team Emirates), and attacked first as the ascent ramped up. The only riders that could follow were Van der Poel, Van Aert and Ganna, who joined forces to form a quartet at the front.
With 5.5km to go, Van der Poel kicked viciously down on the pedals. So viciously, in fact, that he quickly drew out a gap to his fellow leaders. The Alpecin-Deceuninck rider crested the Poggio with an advantage of just a few seconds, picking his line carefully on the descent to further distance those chasing.
As he hurtled under the flamme rouge, it was clear that victory was his. The Dutchman punched the air as he crossed the line, and celebrated by kissing his partner on Sanremo's Via Roma. Behind, Ganna pulled through to the front, holding off Van Aert to take second place.
Van der Poel's win, his first of the season, sees him tick off a second Monument on his rapidly-expanding palmarès. Can he add a third at Paris-Roubaix? Though perhaps a better question is: can anyone stop him?
Milan-San Remo 2023: Abbiategrasso to Sanremo (294km)
1. Mathieu van der Poel (Ned) Alpecin-Deceuninck, in 6-25-23
2. Filippo Ganna (Ita) Ineos Grenadiers
3. Wout van Aert (Bel) Jumbo-Visma
4. Tadej Pogačar (Slo) UAE Team Emirates, all at 15s
5. Søren Kragh Andersen (Den) Alpecin-Deceuninck
6. Mads Pedersen (Den) Trek-Segafredo
7. Neilson Powless (USA) EF Education-EasyPost
8. Matej Mohorič (Slo) Bahrain Victorious
9. Anthony Turgis (Fra) TotalEnergies
10. Jasper Stuyven (Bel) Trek-Segafredo, all at 26s
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