The Simon and Ed Crisford-trained Sharmardal gelding had finished second to Missed The Cut in the Listed Churchill Stakes at Lingfield in November, before winning two Grade Two races over a mile and an extended nine furlongs at Meydan.
Back to a mile-and-a-quarter in the $12million Dubai World Cup, he was running the race of his life under big-race jockey James Doyle, who looked to have his rivals beaten turning in.
However, the 11-4 chance was run down in the final furlong by Ushba Tesoro and just held on for second from Emblem Road.
"He ran his heart out and did us all proud," said Ed Crisford. "It was a great performance from him and he proved himself among the top dirt horses in the world.
"They just went so quick up front – they were going some serious fractions, and that set it up for the deep closers, but all credit to him to keep going."
Having tracked Saudi Cup winner Panthalassa and outsiders Remorse and Bendoog, who had set a searching gallop, Doyle set sail for home from the final turn.
After burning them off, Algiers led a furlong and a half out, only for Yuga Kawada aboard the Noboru Tagaki-trained Japanese raider fly past in the final 110 yards.
"All the horses around him stopped fairly quickly," added Crisford. "I think coming into the straight, we all thought he'd won, but that last furlong was excruciating.
"It wasn't to be, but he did us all proud. It is great for the team at home. It's not so bittersweet. If someone had said to me in December, when he had got beaten in a Listed race at Lingfield that he would finish second in a World Cup, I wouldn't have believed it.
"He has come a long way and he will go on a holiday now."
The Hamdan Sultan Ali Alsabousi-owned six-year-old has now won just short of £2.5m in prize-money in his 21-race career.
Though winning four of his 14 starts on turf, he has only once finished out of the first two in all seven on artificial surfaces, including three wins, and connections are keen for him to ply his trade in that sphere from now on.
"I don't think we'll see him on turf again and I don't think we will see him until the end of summer at some stage," added Crisford.
"Obviously it is early days, and we are long way from it, but you've got to be potentially thinking of something like a Breeders' Cup."
Meanwhile, the stable's dual Group Two-winning miler Jadoomi could bid for success at the top level this term.
Having taken Goodwood's Celebration Mile, Jadoomi followed up in the Boomerang Stakes at Leopardstown in September.
He was last seen when beaten a length and a half by Bayside Boy in the Queen Elizabeth II at Ascot in October.
Crisford said: "Jadoomi is good. He is coming along. His first target would be the Lockinge at Newbury, depending on ground.
"He's doing nicely and hopefully by mid-May he'll be ready to go."
