Alamshar has been well backed on Monday to give his owner, the Aga Khan, his second Derby victory in a week following Dalakhani's win in the French version at Chantilly on Sunday.

Both Ladbrokes and William Hill reported plenty of interest in Alamshar and have cut his odds for the Vodafone Derby to 7/2 from 4/1. Brian Boru remains their favourite at 3/1 and 11/4 respectively.

Alamshar's jockey, Johnny Murtagh, reports his mount "in great form" ahead of the Irish rider's attempt to win a third blue riband in the last four years at Epsom on Saturday.

Murtagh's victories in the premier Classic came on Sinndar, trained like Alamshar by John Oxx, in 2000 and High Chaparral last year.

Comparing those horses with Alamshar, Murtagh told attheraces: "He's a good balanced horse and I think he saves the best for the track, so he has quite a few similarities to both Derby winners I've ridden."

Murtagh has been pleased with Alamshar's build-up for the big race.

He said: "He's going very well. I rode him in his last bit of work. He followed his lead horses, he went between them, he worked well, he's in great form and Mr Oxx is very happy with him."

Alamshar will be attempting a mile and a half for the first time on Saturday, which gives the rider some cause for concern.

"Stamina is the only worry I have," Murtagh said. "He's by Key Of Luck, but the dam stayed well.

"He's a relaxed horse and I think he'll give himself every chance.

"The Aga Khan's horses have stamina in the mares and hopefully it'll come through and stand him in good stead on the day."

Alamshar, the winner of both his starts as a juvenile, lost his unbeaten record in slightly unfortunate circumstances on his reappearance at Leopardstown in April, going down by by half a length to Balestrini.

Recalling the race, Murtagh said: "I followed the wrong one that day. I followed Mick (Kinane on Alberto Giacometti) and the pacemaker got away on me, but I made up five lengths in the last half-furlong and that's when I thought we might have a serious contender.

"He had been working well at home but he didn't feel like anything special, but when I rode him that day he really impressed me the way he quickened up."

Alamshar went one better next time when beating The Great Gatsby and Brian Boru by a head and two and a half lengths in Leopardstown's Derrinstown Stud Trial Stakes - a race which also went to the last three winners of the Derby - after an interrupted preparation.

Despite the narrowness of the winning margin, Murtagh had been happy with his mount's performance.

He said: "He showed his battling qualities. He didn't have a great week beforehand. He had a few little problems and wasn't at his best.

"I was just delighted he won because it was dreadful conditions. There was a thunderstorm before the race, it was windy and raining.

"He went to win well and then he just died a little bit on me.

"He showed he has the heart for battle and he's going to need that come Epsom."

Brian Boru was conceding 5lb to Alamshar that day but Murtagh is hopeful he can confirm Leopardstown placings with Aidan O'Brien's charge.

He said: "He's 5lb better off but I think my fellow will improve on that run.

"His preparation has gone great since Leopardstown. I rode him on Friday morning and he was fresh and well.

"The ground is good at the moment and I hope it stays like that. We are looking forward to getting him there in one piece and hope he puts up a good show."

Brian Boru regained his position at the head of the betting on Friday after heavy support for the son of Sadler's Wells and negative rumours surrounding his market rival Refuse To Bend.

Brian Boru was having his first race of the season at Leopardstown.

"We were happy with his run," O'Brien told attheraces. "It was obviously his first competitive race this year. It was a little bit slower than we would have liked but he came home well and we've been happy with him since.

"He's a clever, very intelligent horse with a lot of natural ability."

O'Brien, who is bidding to win the blue riband for a record third year on the bounce following the victories of Galileo and High Chaparral, also has Alberto Giacometti, Balestrini, The Great Gatsby and Handel in the race, which has a total of 24 entries remaining after Monday's confirmation and supplementary stage.

Alberto Giacometti finished third to Dalakhani and Super Celebre in the Prix Lupin last time and O'Brien said: "He's had two runs this year and improved a lot from the first to the second. We are hoping for a good run."

Speaking about The Great Gatsby O'Brien added: "He had a very nice run first time out and our horses show improvement for their first run so hopefully he will run a good race also.

"Balestrini is also a possible. He won the trial at Leopardstown and he was fourth in the Lupin. We'd like a nice bit of ground for him."

As expected, Dutch Gold, Kris Kin and Norse Dancer have been added to the field at a cost to connections of £90,000 for each horse, giving the Derby a total prize fund of £1,470,000, making it the richest race ever run in Europe.

Clive Brittain could be double-handed in the Derby, having supplemented Victor Chandler Chester Vase winner Dutch Gold and left in his Italian Derby third Lundy's Lane.

Dutch Gold is a definite runner, but a decision on Lundy's Lane will be made later in the week.

The Newmarket trainer has been happy with Dutch Gold's progress since his six-length call over Derby rival Summerland on the Roodee.

He said: "Dutch Gold is in very good form. I'm delighted with the way things have gone.

"He'll be going there with a big chance."

Explaining the reasoning behind leaving Lundy's Lane in the blue riband, Brittain said: "We decided on leaving him in to have a look. A decision as to whether he will run will obviously be made before Thursday (final declaration stage).

"There were several factors. What was and what wasn't going to run, how many would be in? We were already in and we supplemented Dutch Gold at £90,000, and it was only going to cost £2,500 to have a look with Lundy's.

"We didn't throw the money away. He's very well in himself and he's taken his Italian run very well."

The safety limit for the Derby is 20, so four of those still in will not run and one of those who could be eliminated is the John Gosden-trained Summerland.

"He will be declared. We are keen to run him but he might not get in. He's on the borderline," Gosden said.

"J Fortune will ride. The horse worked this morning and worked well. His form links in well with Alberto Giacometti (beaten a head in the Criterium de Saint-Cloud).

"Our horses are firing at the moment but we need to get in."

Seb Sanders will partner outsider Unigold for Ed Dunlop.

Unigold finished second to High Accolade in the Predominate Stakes at Goodwood last time to earn a tilt at the Derby.

"He'll probably go off a 500-1 shot but he's in good form and he should stay," Dunlop said.

"I think the Predominate was a good trial. I think the winner is a good horse.

"There's no pressure, we'll just go and enjoy the day."

Officials at Epsom are keeping an eye on the weather before putting any more water on the Derby course.

Clerk of the course Andrew Cooper said: "We got four millimetres of overnight rain, which is about half of what we were forecast.

"The going is unchanged at good, good to firm in places. I'm perfectly happy with the ground at the moment but in a way I would have preferred to have a little more rain last night because it is forecast to be dry for the next 48 hours and some of the good to firm areas could be a bit quick by Wednesday.

"It is now looking like we might get some rain later in the week. We will just have to keep an eye on it and see how things go but at the moment I'm perfectly happy."

The news of fast conditions will not help Godolphin's Derby hopes Graikos and New South Wales.

On the Godolphin website racing manager Simon Crisford said: "We are not sure yet whether Graikos or New South Wales will run. It all depends on the state of the ground, as both horses prefer slightly softer conditions than prevail at the moment."

Both horses are reported to be well and a decision will be left until the declaration stage on Thursday.

Michael Hills will ride Dunhill Star for his father Barry, who has saddled the runner-up in the Derby four times and the third once.

Coral have cut Brian Boru to 5/2 from 11/4 following continued support. The same firm eased Refuse To Bend to 4/1 from 7/2 having not seen a penny for the Dermot Weld runner for over a week.

"Coral has a huge ante-post position on Brian Boru which is largely a legacy from Cheltenham as he is the last leg in hundreds of multiple bets," said Coral spokesman Simon Clare.