The 27-year-old has been snapped up by owners Middleham Park Racing to partner the Richard Hannon-trained son of High Chaparral, who is a general 14-1 chance to land the world’s oldest Classic.
Few jockeys have a better big-race record on Town Moor than the Newmarket-based Italian, who struck aboard the Roger Varian-trained Kingston Hill in 2014 and followed up 12 months later with Simple Verse for Ralph Beckett.
Atzeni, who also won the Racing Post Trophy four years in succession from 2013 to 2016, said on Monday: “I’m glad to get the ride on him. Jamie Spencer was meant to ride him, but I don’t think he is at Doncaster.
“He is 100 per cent an ideal Leger type and that is why they are running him in it. Kew Gardens looks the one to beat, and Lah Ti Dar will be hard to beat if she turns up, but he has done nothing wrong all season.
“It is not like he is a 50-1 shot, he goes there with a chance. I’m lucky to get the ride on him and I’m looking forward to it. I’ve never ridden him before, but I’ve seen plenty of him. The trip will not be a problem.
“He does need to relax as Doncaster is a long, galloping, fair track and it is important for horses to relax.”
On his affinity with the South Yorkshire circuit, Atzeni added: “It is just one of those things.
“I’m usually away for the Lincoln and November Handicap, but I’ve been very lucky to ride some good horses in the St Leger, Racing Post Trophy and Doncaster Cup.”
As for Marlborough handler Hannon, he believes Atzeni is an ideal partner for his dual winner, who finished second in the Geoffrey Stakes at Newbury on his most recent start.
Hannon said: “We’ve got Andrea Atzeni for the Leger, which will suit him. He is a very good jockey around there.
“Hopefully he will get him to settle, let him drop his head and get him relaxed through the race to allow him every chance of getting the trip.”
Ante-post favourite Kew Gardens is among 15 possible rivals.
The Queen’s Vase and Grand Prix de Paris hero enhanced his Classic claims in defeat last time out when finishing a staying-on third in the Great Voltigeur Stakes at York, where he was burdened with a Group One penalty.
Trainer Aidan O’Brien said: “We were delighted with Kew Gardens at York.
Watch our experts analyse the Great Voltigeur Stakes
“It wasn’t ideal under the penalty, but he had to have the run and we just thought that was the perfect place to give him his prep.
“Ryan (Moore) was delighted with him, he obviously stays further and we always thought that Doncaster would suit him.
“He had one disappointing run and that was in the Derby and he disappointed us a little bit at Lingfield, so maybe he’s a horse that just likes a level track.
“We rode him forward enough in the Derby, too, and maybe if we’d taken our time with him that might have suited him better.”
The other Ballydoyle confirmations are Flag Of Honour, Southern France, The Pentagon, Nelson, Giuseppe Garibaldi and Zabriskie.
Joseph O’Brien, successful as a rider on Leading Light for his father in 2013, has a strong contender in Latrobe, winner of the Irish Derby. Paddy Power and SkyBet make him 11-1.
Latrobe beat only one horse home in the Juddmonte International at York on his most recent outing, but O’Brien felt both tactics and the 10-furlong trip had been against his charge that day.
He said: “He’s in good form. We probably got our tactics wrong a bit at York, but obviously we also found out that we needed to go back up in trip.
“It was a bit of a fact-finding mission at York as we had the easier option of running him in the Great Voltigeur under a penalty. But I suppose it made more sense for us to find out exactly where we are with him. We had to rule it out or in.
“He didn’t run too badly at all and we were probably a bit too positive in a race where you wanted to be sitting a bit further back. He was a bit outpaced and he stayed on well, but after that we said we would go straight back up in trip.”
Great Voltigeur scorer Old Persian, trained by Charlie Appleby, is in the list along with two other Godolphin-owned colts, Loxley and Brundtland.
Appleby is keen to let Old Persian, a general 6-1, take his chance, but will be keeping a careful eye on the Town Moor weather.
He said: “As long as we get nice ground, then he’s a contender. I wouldn’t want him to be racing on anything bottomless as it just turns into a slog.
“We tried to give him a few easy days after York, but he didn’t appreciate that and was getting a little too fresh. He enjoys his work and is very straightforward.”
With Wells Farhh Go ruled out through injury, the big hope for the north is the Mark Johnston-trained Dee Ex Bee, who was runner-up in the Derby. He is a general 12-1.
Lah Ti Dah, impressive winner of the Galtres Stakes at York last month in her first race since May, has been left in by trainer John Gosden. BetVictor make her 5-1 but she is as short as 3-1 elsewhere.
A second filly, Maid Up, was added to the race at the supplementary stage. Andrew Balding’s charge showed her appreciation for a test of stamina when winning the Group Three March Stakes at Goodwood last month and connections have duly stumped up the £50,000 fee. She is available at 20-1.
Tom Dascombe’s Proschema completes the list.