Dare we take on Aidan O'Brien? Here are three Ballydoyle runners I'm keen to oppose this week

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It's hard to talk about a stable going out of form without annoying someone, and I don't just mean the trainer concerned. To some readers, it can look like kicking a person when they're down.

But I have fewer fears on that score when the trainer in question is Aidan O'Brien. He's had so much success and there will be lots more to come. The odd bump in the road is not going to bother him.

Even Ballydoyle can't win all the time and we seem to be going through one of its slower periods, at least as regards Group races. May, June and July were terrific; O'Brien's runners brought home 14 top-class prizes over those three months. 

Almost a month has passed since Sun Goddess won the Phoenix, the yard's sole Group 1 win in August. Yes, I know - we should all have problems like that.

York was okay. Sun Goddess won again, in the sales race, and Haffner took the Acomb. But Constitution River let his fans down, Christmas Day was comfortably held in the Voltigeur, Marco Polo was disappointing in the Gimcrack and Mission Central faded in the Nunthorpe.

Sun Goddess: shone brightest in AugustCredit: John Grossick (racingpost.com/photos)

Ballydoyle has had four winners over the past fortnight, three in maidens. But when the quality races came over the weekend, results didn't go their way.

Causeway was a one-paced fifth in the Nashville Derby, admittedly on a track that seemed not to suit him. Gstaad was disappointing for the first time this year in the Prix du Moulin. Benvenuto Cellini was way below his best in the Prix Niel, his jockey hard at work to keep him straight in the final two furlongs.

When you list a few bad results like that, one after another, you run the risk of convincing yourself something's really wrong. But these are all individual horses with their own particular needs, which were probably not met by the circumstances of this weekend.

On the other hand, we're getting towards season's end and some of these horses might not be feeling as fresh as they were.

Another factor is that our expectations of O'Brien-trained runners are always high, sometimes unrealistically so. If they don't win, we feel something's amiss. The reality is that other trainers also have quality animals and sometimes the ball bounces their way.

So how do you feel about Ballydoyle's runners right now? It's a key question if you're going to get involved this weekend because O'Brien will be represented in all the good races, or close to all.

Benvenuto Cellini: below his best in FranceCredit: Patrick McCann (racingpost.com/photos)

Are you worried, in light of recent results? Or are you hoping that everyone else worries, so you can get a couple of points bigger than expected about the most likely winner?

Full disclosure: I have a well-established history of spotting trends and sequences and streaks right before they come to a shuddering end. At times, it has felt like I could change the course of events, just by saying: "Gosh, look at this..." And immediately, the thing I was pointing at would evaporate.

If O'Brien absolutely cleans up at Doncaster, Leopardstown and the Curragh, you and I can meet up again here next Monday and say: "Yep. I know what happened there. I know what caused that."

For now, signs are pointing the other way. Ballydoyle has had less success in recent weeks than the market expected.

If that continues for another week, who are the vulnerable O'Brien runners? I've come up with three that I'm interested in opposing.

1) Christmas Day 7-4 St Leger

Full respect to the Derby winner but two subsequent defeats show that he's anything but invincible. His Voltigeur run seemed a slight step back from the quality of his two runs in June, so there's an obvious chance of a progressive three-year-old spoiling things for him at Doncaster.

Christmas Day: won a strange DerbyCredit: Alan Crowhurst (Getty Images)

The extra distance should help him but it looks like drying weather in Doncaster at the end of this week, so he won't get the mud that helped him at Epsom. With talented rivals like Enceladus due to take him on, I'm surprised he's this short.

2) Giant Sequoia Golden Fleece or National Stakes

This son of Frankel evidently comes with a big reputation, which he has yet to fully justify. Beaten on his debut at odds of 4-9, he got it right next time and recently followed up in the Group 2 Futurity.

But he took an age to get past a stablemate that day. He looks like a middle-distance three-year-old in the making and might easily be vulnerable as he steps into a top-class race for the first time. 

Giant Sequoia: lofty reputationCredit: Patrick McCann (racingpost.com/photos)

The National Stakes, over seven furlongs, seems his preferred target but I doubt his pace for that trip at this level. He's also in Saturday's Golden Fleece over 1m1f, which could be a better fit. 

3) Sun Goddess, 6-5 Moyglare Stakes

After her last couple of runs, she's one of the most exciting horses in training but that tends to ensure she'll be a shorter price than she should be. On Sunday, the step up to seven furlongs could be her undoing, especially if it's a wet week. 

Speed is her weapon. Maybe it will still work over an extra furlong but she'll be coming up against specialists at this trip and they ought to be finishing stronger than her.

Green Empress is especially interesting, having got close to Sun Goddess in June, when she ran on well in the final 100 yards. Both have improved since. Green Empress looks like being a lot better at this distance than sprint trips.

Constitution River: harder to opposeCredit: Edward Whitaker (racingpost.com/photos)

It's so tempting to oppose Constitution River in the Irish Champion Stakes, considering he's favourite to turn around York form with Item, who perhaps deserves to be taken more seriously.

But Constitution River seemed to boil over before that race and could improve quite a bit if he stays cool this time. I just sense this may be the wrong time to get in his way but we'll learn more about the shape of this race during the week.  

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Racing Post+ Ultimate subscribers can get a fantastic mix of news, tips, comment and insight sent straight to their inbox every day, from Chris Cook's award-winning morning newsletter The Front Runner every weekday at 7.30am to different weekly emails from the likes of Tom Segal, Paul Kealy and Lee Mottershead every evening at 6pm every evening as part of The Ultimate Daily.