Unbeaten Artur Beterbiev has 17 knockouts from 17 wins, and the Russian will defend his WBC and IBF belts here.
Smith Jr, meanwhile, enters the Madison Square Garden Theater as WBO champion and with a professional record of 28-3 (22 KOs).
The American, 32, must do what no other fighter has done and hand Beterbiev the first loss of the Russian’s pro career this weekend if he is to retain his gold and collect the 37-year-old’s titles.
Last time out, Beterbiev stopped Marcus Browne in December for a ninth-round victory, while Smith Jr also won in Round 9 of his most recent fight, beating Steve Geffrard in January.
Here’s all you need to know.
When is it?
The fight will take place on Saturday 18 June at the Madison Square Garden Theater in New York City.
The main card will begin at 2am BST (6pm PT, 8pm CT, 9pm ET) on Sunday 19 June, with ring walks for the main event set for approximately 4am BST (8pm PT, 10pm CT, 11pm ET).
How can I watch it?
In the UK, Sky Sports will air the fight live. It will also be available to stream live on the broadcaster’s Sky Go app.
In the US, ESPN+ will stream the bout live.
Beterbiev – 1/12
Draw – 33/1
Smith Jr – 11/2