Paul Nicholls and Ruby Walsh suffered their second major reverse of the week as Master Minded was eclipsed by Voy Por Ustedes in the John Smith's Melling Chase at Aintree.

The champion trainer and owner Clive Smith found themselves in the second spot in the winner's enclosure after Kauto Star was nailed on the opening day of the meeting, and were back there again as Master Minded wearily crossed the line 18 lengths in arrears.

Voy Por Ustedes was a similar distance behind Nicholls' charge when he floated to victory in the Champion Chase last month, earning himself the lofty title of the highest-rated chaser in training.

But he was stepping into unknown territory on British soil as he tried two and a half miles.

Despite his unassured stamina, Master Minded was sent off the 2-5 favourite and nudged into the lead turning for home, taking the Alan King-trained winner with him.

Master Minded has readily disposed of his rival in the past but this time Voy Por Ustedes (5-1) matched strides.

A mistake from Master Minded at the second-last then handed Robert Thornton's mount an advantage which kept being extended to the line.

King said: "To be honest I thought we were going to finish second, but two and a half miles was more likely to suit us than Master Minded.

"You can't be frightened of one horse, although I have to say I was devastated when I heard Paul was thinking of running his horse here.

"But plans can't change. I was not confident but when we got in a scrap, I knew Master Minded didn't get two and a half (miles) in France.

"Choc (Thornton) felt the ground had a lot to do with it too. He handles the soft but is a much better horse on proper good ground.

"I don't think we'll be going down the two-mile, Champion Chase route again.

"We'll be looking at two and a half now, and the King George is very much in the equation."

Thornton added: "I was hopeful, not confident. I thought if Master Minded ran a bit flat or if he didn't stay the trip we would take advantage.

"There's obviously an excuse for Master Minded, but we took full advantage and he galloped all the way to the line."

Sponsors Stan James make the winner a 6-1 chance for the King George, while quoting him at 5-1 for the Champion Chase - for which totesport eased Master Minded out to 5-4 from evens.

Any chance of stepping up to three miles was immediately ruled out for Master Minded and the five-year-old will be kept over the minimum distance next winter.

Nicholls said: "He has run a good race, but Ruby said he didn't stay - it is as simple as that.

"The mistake didn't help, but he was running on empty at that stage and we now know he is a two-miler.

"He had never won over two and a half miles in France, but Ruby did say to me after Sandown that he might want that trip.

"I was amazed before Newbury how much he had improved and he was devastating over two miles there, but at least we know now that we should stick to two miles.

"We won't be thinking 'is he a King George horse' as he will be running over two miles.

"Voy Por deserved to win a big race and we owed him one really.

"We will rough him off now and come back for the Tingle Creek."

Smith remained in good heart despite another huge reverse, and joked: "It was that second-last fence again - we'll have to get it removed for next year!

"Ruby just said he didn't stay, but the horse seems to be fine and this makes you value every win.

"We'll go for the Tingle Creek and Champion Chase next season with another race in between."