It will be another big international weekend for Irish-trained horses with Aidan O'Brien launching a major assault on Britain today before switching his focus to Canada tomorrow night.

The Ballydoyle trainer sends six horses to Doncaster this afternoon with four of them destined for the last cross-channel Group One target of the year in the Racing Post Trophy.

A fifth success in that race will be O'Brien's major focus but a win there will also wipe out the just-over-£100,000 lead Michael Stoute currently holds in the British trainers' championship.

With that in mind it is surely no coincidence that another three Ballydoyle inmates head for Newbury where Colm O'Donoghue will team up with Hurricane Cat in the Group Three Horris Hill, De Laurentiis in the Group Three St Simon Stakes and Queen Cleopatra in the Listed Radley Stakes.

Kieren Fallon will ride the apparent first-string Septimus in the Racing Post, a race he won last year on Motivato, and an event O'Brien has won four times before including with the subsequent Derby hero High Chaparral in 2001.

Almost immediately afterwards both Fallon and Michael Kinane, who rides the Stoute hope Best Alibi in Doncaster's highlight, will head for Toronto and the $2 million Canadian International at Woodbine tomorrow night.

Kinane won that Grade One on O'Brien's Ballingarry in 2002 and now teams up with the Italian-trained favourite Electrocutionist on whom he won the Juddmonte at York in August.

Sulamani completed the York-Woodbine double last year but it looks a stronger race this time with O'Brien pitching in Yeats and Dermot Weld sending Grey Swallow, who will be Pat Smullen's first ride back after suspension.

The ground at Woodbine is currently reported to be firm but rain is forecast and Weld's representative Bobby Dolan said yesterday: "It usually depends on the ground for Grey Swallow and if he gets it soft he will be bang there."

Top-level Irish interest won't end there, however, as the Con Collins-trained Chelsea Rose is another Group One runner tomorrow in the Premio Lydia Tesio at Capannelle in Rome.

Last year's Moyglare runner will again be ridden by Pat Shanahan but faces a big task in a 10-strong field that includes the Prix de l'Opera winner, Kinnaird, and Dubai Surprise from Godolphin.

Tony McCoy is at Fairyhouse today for a couple of novice chase rides including Man About Town in the two-mile Beginners Race. However, the Galway Hurdle runner-up Tiger Cry looks an interesting option here while Kerryhead Windfarm is worth another chance in the other novice event.