Bookmakers are braced for a €500 million Cheltenham Festival bonanza as the biggest betting week of the year kicks off at the Cotswolds today.

The four-day Festival will see close to half a billion being wagered across Ireland and the UK and Willie Mullins has been the punters’ pal as the Closutton maestro closes in on a century of Cheltenham winners.

Having secured a record haul of 10 last year, Mullins stands on 88 Festival victories and many of his leading contenders are sending shivers down the spines of the bookies.

“If Galopin Des Champs (in the Gold Cup) comes home with the rest of the Willie Mullins favourites, we are looking at a huge liability,” BoyleSports said.

“It is likely one of the biggest risks the business has faced since Annie Power in the Mares Hurdle (2015), before she fell at the final hurdle.”

Ladbrokes report Mullins’ Facile Vega as their biggest concern on the opening day should he prevail in the Supreme Novices’ Hurdle (1.30) while Honeysuckle will also hit them hard should she bow out on a high in the Mares’ Hurdle (4.10) under Rachael Blackmore.

“Facile Vega and Honeysuckle are our major concerns,” Nicola McGeady of Ladbrokes said: “The dream start to the Festival for us would be getting the Willie Mullins favourite beaten.”

After taking the last three editions of the Prestbury Cup (by a combined 58-25), the Irish raiders are expected to run riot once again over their British counterparts with Mullins and Co 1/25 to prevail again.

Meanwhile, Blackmore says she is craving the pressure which the four days bring as she bids to continue her unprecedented recent success. She was crowned leading rider at the Festival in 2021 with six winners – the first female rider to achieve that feat – before adding the Gold Cup on A Plus Tard last year.

“There is so much expectation going into a week like this but it is pressure that you want. I want to feel it going into the week because that, in turn, means I have got some very good rides,” she wrote on her Betfair blog.

“It is pressure but it is, strangely, pressure that you crave and that you want. It just means that you are going to Cheltenham with some good rides. Everyone has different ways of managing it but you just have to be thankful that it is there and get on with it.”