Masterofthehorse looks an ace for O'Brien's nine-card brag

That the Derby jigsaw is incomplete should be no surprise at this stage – the picture will not be revealed until around 10 to four next Saturday – but with just a week to go the contents of the box are not even known yet. Aidan O'Brien still has nine horses engaged and no decision on the participation of last year's champion two-year-old Crowded House will be made until Monday.

It might be possible then to start to put the pieces of the puzzle face up on the table, but until the Ballydoyle contingent and riding arrangements are confirmed when the final declarations are made for the £1.25m Epsom showpiece on Thursday, the straight-edged ones won't be there. And, in the latest shuffle, the O'Brien runner to come in for a show of support is Masterofthehorse, backed into 9-1 from 20-1 yesterday.

Stable jockey Johnny Murtagh test-drove the son of Sadler's Wells in a trial at Chester earlier this month when, from miles off the pace, he failed to catch his trailblazing stable-mate Golden Sword. Given the task he was set, it was a highly creditable performance from the colt, whose sister Alexandrova won the Oaks three years ago.

O'Brien, quite reasonably, is giving nothing away, even though his charges occupy five of the first seven slots in the betting. He might have an idea about the pecking order and it is probably fair to say that he rates Fame And Glory, say, above Johann Zoffany, who gave his 16-year-old son Joseph his first victory as a jockey in a Leopardstown handicap on Thursday night. But with that many eligible horses, he cannot be certain of the absolute comparable merit of the perceived best ones; it is not the Ballydoyle way to place the gun to the head at home.

And anyway, the racecourse is the test, not the exercise grounds, and nothing can make a fool of a man like a horse. Last year, the best-placed of the O'Brien runners was the 33-1 shot Washington Irving in fifth; two years before that it was Dylan Thomas, third at 25-1; and in 2003 The Great Gatsby at 20-1.

Even his most recent winner, High Chaparral seven years ago, at 7-2, was longer-priced than his stablemate and runner-up Hawk Wing, the choice of the then stable jockey Mick Kinane.

Murtagh, who rode High Chaparral and has his brother Black Bear Island as an option this time round, will know what he has felt, but appears none the wiser either. After riding work in Co Tipperary yesterday morning he told his Twitter followers: "All horses are going well and it's very hard to split them." Twits might like to know there have been only two dead-heats in the Derby.

Frankie Dettori, successful on Authorized two years ago, will be faced with Hobson's choice; his retaining stable Godolphin have mustered just Kite Wood, a 25-1 shot, for the Investec-sponsored premier Classic.

In Newmarket, the tradition is that Derby contenders have their last serious work round a bend on the centuries-used Limekilns gallop; early yesterday, on a perfect summer morning, the Galileo colt (no fewer than 15 of the 20 horses still engaged in the Derby running are by either Sadler's Wells or his sons Galileo, Montjeu and High Chaparral) and Dettori stretched three lengths clear of the Italian Derby winner Mastery.

Kite Wood, headhunted by Godolphin during the close season, finished a close and encouraging fifth to Black Bear Island on his seasonal debut in the Dante Stakes 16 days ago. But although 11 winners of the York trial have gone on to score at Epsom, including three of the last five, no horse beaten in it has won a Derby.

"Good, solid, routine stuff, no fireworks," said Godolphin's racing manager, Simon Crisford, in down-to-earth mode after yesterday's spin. "He's in good shape, the step up to a mile and a half will suit him well, and it seems he's improved since York, as we expected him to. But he will need to have done to be a live contender."

Crowded House, the winter Derby favourite, came in three places behind Kite Wood on the Knavesmire. A snuffly nose was blamed for his flop and, though he too worked well yesterday morning, in his case behind closed doors on the Manton gallops, he has yet to be given the green light. "He had a good blow," reported his trainer, Brian Meehan, "he'll work again on Monday, and then we'll know."

With the Epsom Classics so close – the Oaks is on Friday – today's domestic fare has something of a "before the Lord Mayor's Show" ring to it. At this stage of proceedings, yards involved with the big parade will particularly welcome any success that confirms the well-being of their inmates; Godolphin can oblige with course winner Yamal (3.25) at Goodwood and Henry Cecil, who has the Oaks third favourite Midday under his care, with Montbretia (2.35) at Haydock.

The day's top race in terms of both prestige and value is the seven-furlong Group Three at the Lancashire venue. Main Aim steps up in class a couple of rungs after treating a field of handicappers with contempt last time. With Group One sprint entries, he is clearly highly regarded and seems to be the progressive sort with which his stable excels. But a chance can be taken with Tariq (3.05), who ran better than his placing suggested at Newbury two weeks ago and returns to his optimum distance.

Cox strikes twice to show success can be infectious

When an iron is hot, it can be red-hot. Lambourn-based Clive Cox, one of the country's most progressive young trainers, is heading for easily his best season and a double yesterday afternoon at Goodwood took his score to four winners from 11 runners in six days. First up was Xtension, who marked himself as an above-average juvenile with a stylish debut as 5-2 market leader; then came Louise Bonne, who defied her odds of 33-1 to get off the mark in the fillies' maiden.

She took Cox, in his 10th year at Beechdown Farm, to 22 winners this season; his previous best was 33. Xtension, who scored by four lengths under Adam Kirby, may have earned a shot at the Coventry Stakes at Royal Ascot. "He's very exciting and will improve a bundle," Cox said. "I have to admit that I didn't think the filly was up to winning, but sometimes success is infectious."

It seems to be for the three-year-old Global, who won for the third time in nine days when he took the mile handicap, defying topweight and a 12lb penalty. "Despite winning three races, he's won us less than 10 grand," said his trainer, Richard Hannon.

One of the most troubled relationships of the last jump season has broken up with yesterday's news Sam Thomas, No 2 rider for Paul Nicholls, is now No 1 at Tom George's yard. Thomas, who won last year's Gold Cup on Denman, can look forward to another high-class chaser in Nacarat.

Chris McGrath

Nap: Falcativ (4.40 Doncaster)

NB: Montbretia (2.35 Haydock)