The Argentine midfielder, 29, was being chauffeur-driven in a $92,000 Mercedes people carrier when it flipped over on the A12 this afternoon.
Other motorists watched in horror at V‑CLass — with a West Ham number plate — landed on its side in a crumpled mess.
Firefighters raced to the scene but Lanzini miraculously walked out unhurt. He was checked at the scene but ruled well enough to carry on to training.
It is believed the attacker was being driven back to the training ground on his return to the country after international duty.
A source said: “It’s a miracle he’s alive, from what I’ve heard.
“This was an incredibly near miss and could have killed Lanzini and the driver.
“It’s common for West Ham players to use a chauffeur service — especially for those who live in town.
“They were on a dual carriageway so it could have caused complete carnage.
“Just goes to show, it doesn’t matter how much cash you have — we’re all just as vulnerable to a smash like this.
“Thank goodness he was okay.”
The crash is said to have taken place after 2.30pm today as Lanzini headed to the club’s Rush Green complex, in East London.
The dad-of-one Lanzini, who is capped for Argentina, was expected to be available for West Ham’s squad to face Everton on Sunday.
Lanzini has faced a string of driving offences since joining the Hammers in 2015 — initially on loan before a $11.8m transfer — including speeding, driving without insurance and failing to produce.
He has previously driven a $120,000 Range Rover.
Police and fire services were called to the scene.
A spokesman for West Ham confirmed the crash saying: “It happened on the A12 near the training ground.”